LIGNOPHYTA

True roots +; lateral meristems: cork cambium producing cork abaxially, vascular cambium producing phloem abaxially and xylem adaxially.

EXTANT SEED PLANTS/SPERMATOPHYTA

Plant woody, evergreen; nicotinic acid metabolised to trigonelline, (cyanogenesis via tyrosine pathway); primary cell walls rich in xyloglucans and/or glucomannans, 25-30% pectin [Type I walls]; lignins derived from (some) sinapyl and particularly coniferyl alcohols, thus containing p-hydroxyphenyl and guaiacyl lignin units, (lignins derived from p-coumaryl alcohol, i.e. S [syringyl] lignin units); true roots present, apex multicellular, xylem exarch, and branching endogenous; arbuscular mycorrhizae +; shoot apical meristem multicellular, interface specific plasmodesmatal network; stem with ectophloic eustele, endodermis 0, xylem endarch, branching exogenous; vascular tissue in t.s. discontinuous by interfascicular regions; vascular cambium + [xylem ("wood") differentiating internally, phloem externally]; wood homoxylous, tracheids and rays alone, tracheid/tracheid pits circular, bordered; mature sieve tube/cell lacking functioning nucleus, plastids with starch grains; phloem fibres +; stem cork cambium superficial, root cork cambium deep seated; leaves with single trace from sympodium ["nodes 1:1"]; stomata ?; leaf vascular bundles collateral; leaves megaphyllous [determinancy evolved first, then ad/abaxial symmetry], spiral, simple, lamina with vein density up to 5 mm/mm² [mean for all non-angiosperms 1.8]; axillary buds associated with at most some leaves; prophylls [including bracteoles] two, lateral; plant heterosporous, sporangia eusporangiate, on sporophylls, sporophylls aggregated in indeterminate cones/strobili; true pollen [microspores, i.e. no distal pore for release of gametes] +, grains mono[ana]sulcate, exine and intine homogeneous; ovules unitegmic, crassinucellate, megaspore tetrad tetrahedral, only one megaspore develops, megasporangium indehiscent; male gametophyte development first endo- then exosporic, tube developing from distal end of grain, to ca 2 mm from receptive surface to egg, gametes two, developing after pollination, with cell walls, with many flagellae; female gametophyte endosporic, initially syncytial, walls then surrounding individual nuclei; seeds "large", first cell wall of zygote transverse, embryo straight, endoscopic [suspensor +], short-minute, with morphological dormancy, white, cotyledons 2; plastid transmission maternal; two copies of LEAFY gene, PHY gene duplications [three - [BP [A/N + C/O]] - copies], nrDNA with 5.8S and 5S rDNA in separate clusters; mitochondrial nad1 intron 2 and coxIIi3 intron and trans-spliced introns present.

MAGNOLIOPHYTA

Lignans, O-methyl flavonols, dihydroflavonols, triterpenoid oleanane, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, [cyanogenesis in ANITA grade?], S [syringyl] lignin units common, positive Maüle reaction [syringyl:guaiacyl ratio more than 2-2.5:1], and hemicelluloses as xyloglucans; root apical meristem intermediate-open; root vascular tissue oligarch [di- to pentarch], lateral roots arise opposite or immediately to the side of [when diarch] xylem poles; origin of epidermis with no clear pattern [probably from inner layer of root cap], trichoblasts [differentiated root hair-forming cells] 0; shoot apex with tunica-corpus construction, tunica 2-layered; reaction wood ?, with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides, poor in mannans; tracheid:tracheid [end wall] plates with scalariform pitting, wood parenchyma +; sieve tubes enucleate, sieve plate with pores (0.1-)0.5-10< µm across, cytoplasm with P-proteins, cytoplasm not occluding pores of sieve plate, companion cells from same mother cell that gave rise to the sieve tube; sugar transport in phloem passive; nodes unilacunar [1:?]; stomata with ends of guard cells level with pore, paracytic, outer stomatal ledges producing vestibule; leaves petiolate, lamina [formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, veins (1.7-)4.1(-5.7) mm/mm², endings free; most/all leaves with axillary buds; flowers perfect, pedicellate, polysymmetric, parts spiral [esp. the A], free, numbers unstable, development in general centripetal; P not sharply differentiated, with a single trace, outer members not enclosing the rest of the bud, often smaller than inner members; A many, filament not sharply distinguished from anther, stout, broad, with a single trace, anther introrse, tetrasporangiate, sporangia in two groups of two [dithecal], ± embedded in the filament, with at least outer secondary parietal cells dividing, each theca dehiscing longitudinally by action of hypodermal endothecium, endothecial cells elongated at right angles to long axis of anther; tapetum glandular, binucleate; microspore mother cells in a block, microsporogenesis successive, walls developing by centripetal furrowing; pollen subspherical, tectum continuous or microperforate, ektexine columellar, endexine thin, compact, lamellate only in the apertural regions; nectary 0; G free, several, ascidiate, with postgenital occlusion by secretion, stylulus short, hollow, cavity not lined by distinct epidermal layer, stigma ± decurrent, dry [not secretory]; ovules few [?1]/carpel, marginal, anatropous, bitegmic, micropyle endostomal, outer integument 2-3 cells across, often largely subdermal in origin, inner integument 2-3 cells across, often dermal in origin, parietal tissue 1-3 cells across [crassinucellate], nucellar cap?; megasporocyte single, hypodermal, megaspore tetrad linear, functional megaspore chalazal, lacking sporopollenin and cuticle; female gametophyte four-celled [one module, nucleus of egg cell sister to one of the polar nuclei]; P deciduous in fruit; seed exotestal; pollen binucleate at dispersal, trinucleate eventually, germinating in less than 3 hours, pollination siphonogamous, tube elongated, growing at 80-600 µm/hour, with pectic outer wall, callose inner wall and callose plugs, growing between cells, penetration of ovules via micropyle [porogamous] within ca 18 hours, distance to first ovule 1.1.-2.1 mm, tube moves between nucellar cells; double fertilisation +, endosperm diploid, cellular [micropylar and chalazal domains develop diffently, first division oblique, micropylar end initially with a single large cell, divisions uniseriate, chalazal cell smaller, divisions in several planes], copious, oily and/or proteinaceous, embryo cellular ab initio, minute; germination hypogeal, seedlings/young plants sympodial; Arabidopsis-type telomeres [(TTTAGGG)_n]; whole genome duplication, ndhB gene 21 codons enlarged at the 5' end, single copy of LEAFY and RPB2 gene, knox genes extensively duplicated [A1-A4], AP1/FUL gene, paleo AP3 and PI genes [paralogous B-class genes] +, with "DEAER" motif, SEP3/LOFSEP and three copies of the PHY gene, [PHYB [PHYA + PHYC]].

Evolution. Possible apomorphies for flowering plants are in bold. Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear. This is because some taxa basal to the [magnoliid + monocot + eudicot] group have been surprisingly little studied, there is considerable homoplasy as well as variation within and between families of the ANITA grade in particular for several of these characters, and also because details of relationships among gymnosperms will affect the level at which some of these characters are pegged. For example, if reticulate-perforate pollen is optimized to the next node on the tree (see Friis et al. 2009 for a discussion), it effectively makes the pollen morphology of the common ancestor of all angiosperms ambiguous... For other features such as details of sugar transport in the phloem, their placement on the tree is frankly speculative. Finally, for features such as parietal tissue/a nucellus only one (Nymphaeales) to three cells thick above the embryo sac and a stylar canal lacking an epidermal layer, although plesiomorphous for basal grade angiosperms (Williams 2009), I am unsure where on the tree a thicker nucellus and a stylar epidermal layer are acquired.

[NYMPHAEALES [AUSTROBAILEYALES [[CHLORANTHALES + MAGNOLIIDS] [MONOCOTS [CERATOPHYLLALES + EUDICOTS]]]]]: vessels +, elements with elongated scalariform perforation plates; wood fibres +; axial parenchyma diffuse or diffuse-in-aggregates; tectum reticulate-perforate [here?]; ?genome duplication; "DEAER" motif in AP3 and PI genes lost, gaps in these genes.

LAURALES Berchtold & Presl  Main Tree, Synapomorphies.

(Cork subepidermal); sieve tube plastids with protein crystalloids; nodes 1:?; petiole bundle(s) arcuate; leaves opposite; inflorescence ± cymose; hypanthium +, P spiral; inner staminodia +; stylulus long, (extragynoecial compitum +); ovules 1(-2)/carpel, basal, erect, apotropous; megaspore mother cells several; fruitlets 1-seeded, indehiscent, hypanthium persistent; mesotesta crushed, endotesta tracheidal [seed endotestal], tegmen crushed; embryo long; duplication of the PI gene. - 7 families, 91 genera, 2858 species.

Evolution. Divergence & Distribution. Magallón and Castillo (2009) suggest that stem group Laurales are ca 198.2 and 127.7 million years old - relaxed and constrained penalized likelihood datings - and equivalent ages for the crown group are ca 171.4 and 119.3 million years. See Renner (2005a) for information on diversification of the clade.

The young fruits of Protomonimia have several carpels borne in spirals on a flattened axis, the young seeds having a palisade ?exotesta with inpushings of the anticlinal cell walls and ?mesotestal cells with sinuous anticlinal walls (Nishida & Nishida 1988): If a member of Laurales, it would probably be assigned to stem Laurales because there are several ovules/carpel.

Genes & Genomes. Oginuma and Tobe (2006) suggest that the base chromosome number for the order is x = 11.

Chemistry, Morphology, etc. Soltis et al. (2005b) summarize information on possible synapomorphies for the clade (see also Staedler et al. 2009); von Balthazar et al. (2011) map the distributions of many characters in the order. Isorhamnetin occurs in Lauraceae, Gomortegaceae and "Monimiaceae" (Crawford et al. 1986). The apex of the ovule in some Atherospermataceae is exposed, and this condition may also occur in Siparunaceae and Calycanthaceae (Endress & Igersheim 1997). Little is known of obturator presence in the order, and of many other embryological details, although Endress (1972a) suggests there is considerable variation, some of which may link nicely with phylogeny.

See also Metcalfe (1987) for anatomy, Endress and Igersheim (1997) and Eklund (1999) for general information, Endress (2011a) for references to the distribution of an extragynoecilal compitum, and Kimoto and Tobe (2001) for embryology.

Phylogeny. Calycanthaceae are sister to other members of the clade, but there is little other well-supported structure in interfamily relationships. Gomortegaceae + Atherospermataceae + Siparunaceae form a moderately-supported clade (relationships between the first two supported strongly in D. Soltis et al. 2000, 2011), Monimiaceae + Lauraceae + Hernandiaceae another (the last two had no support as sister taxa in D. Soltis et al. 2000), largely because of morphological data; the clade Hernandiaceae + Lauraceae has strong support (Doyle & Endress 2000, see also Renner & Chanderbali 2000). However, relationships between Monimiaceae, Lauraceae and Hernandiaceae are difficult to work out, this being one of the few cases where there seems to be persistent disagreement between morphology and molecules (Renner & Chanderbali 2000). Here I follow morphology, but molecular data may eventually carry the day (see Renner 2005a for the most recent study, for other phylogenetic work, see Renner et al. 1997 and Renner 1998, 1999; Soltis et al. 2011).

Classification. The contents of Cronquist's (1981) Laurales and Takhtajan's (1997) Lauranae are largely the same as Laurales as they are circumscribed here.

Thanks. I am grateful to S. Renner for comments.

Includes Atherospermataceae, Calycanthaceae, Gomortegaceae, Hernandiaceae, Lauraceae, Monimiaceae, Siparunaceae.

Synonymy: Atherospermatales Martius, Calycanthales Link, Gyrocarpales Dumortier, Hernandiales Martius, Illigerales Martius, Monimiales Berchtold & Presl - Lauranae Takhtajan - Calycanthidae C. Y. Wu, Lauridae C. Y. Wu - Lauropsida Horaninov

CALYCANTHACEAE Lindley   Back to Laurales

Deciduous or evergreen shrubs to trees; tryptamine [calycanth(id)ine] alkaloids +; primary stem ± with vascular cylinder; inverted and entirely distinct cortical bundles +; vessel elements with simple perforation plates; sieve tube plastids with fibers and starch; pericyclic fibres 0; nodes 1:2 [see below]; petiole bundle arcuate, with wing bundles; hairs unicellular; buds with scales; lamina vernation flat to curved; flowers (terminal), large, with cortical vascular system; P many, deciduous, spiral; A with prolonged connective, nectariferous staminodes 10<; (pollen trinucleate); stigma dry; ovules 1(-2)/carpel, micropyle exostomal, outer integument 6-15 cells across, inner integument 4-5 cells across, hypostase +; embryo sac long; fruits ± achenes; testa multiplicative, exotestal cells cuboid, slightly lignified; endosperm lacking paternal contribution, 0.

5[list]/11 - two groups below. China, North America, N.E. Australia (map: from Wu 1983; Endress 1983; Hong 1993; Fl. N. Am. III 1997; Qian & Ricklefs 2004). [Photo - Fruit © Robert Kowal, Flower.]

1. Idiospermoideae Thorne

Flavonols 0, but luteolin, etc. +; (vessel elements with scalariform perforation plates); P ³10, filaments flattened; G 1-2(-5), stigma stout, fleshy, sessile [forming extragynoecial compitum]; outer integument 12-15 cells thick, nucellar beak +; cotyledons (3-)4, massive, peltate.

1/1: Idiospermum australiense. N.E. Australia.

Synonymy: Idiospermaceae S. T. Blake

2. Calycanthoideae Burnett

P 10³; A 5-18, filaments rather slender, (anthers valvate - Sinocalycanthus), pollen equatorially and vertically disulcate; G ³5, stigma filiform, compitum by style coherence; outer integument 5-6(-8) cells thick; cotyledons spirally twisted; n = 11, 12.

4/10. China, North America.

Synonymy: Butneriaceae Barnhart, Chimonanthaceae Perleb

• Calycanthaceae can be recognised by their opposite, entire, exstipulate leaves that smell aromatic. The cortical bundles can be seen with a lens when the stem is cut, and they may also be visible externally as four, raised lines along the stem. The terminal bud often aborts. The large flowers have a bract-covered hypanthium; the inner members of the perianth secrete nectar or bear food bodies. The achenial fruits are attached to the inside of the rather dry hypanthium. [Photo - Flowers]

Evolution. Divergence & Distribution. Crown group Calycanthaceae may have started to diverge in the Campanian, ca. 110 million years ago (Zhou et al. 2006).

Fossils are interesting. Araipa florifera, from the Lower Cretaceous of Brasil, has flowers that externally are very like those of Calycanthaceae, but its leaves are lobed (Mohr & Ecklund 2003); unfortunately, nothing is known of the internal structure of the flower. The late Cretaceous Virginianthus calycanthoides (98-113 million years before present) has been placed in Calycanthaceae. It has small flowers, anthers dehiscing by lateral hinges, and reticulate pollen with a single sulcus (Friis et al. 1994). Its inclusion may change one or two ordinal/family group characters. Thus Idiospermum also has anasulcate pollen, and this may be plesiomorphic for the order, with disulcate pollen being an apomorphy for the rest of Calycanthaceae and inaperturate pollen for the rest of Laurales. Assuming the lateral hinges on the anthers of Virginianthus are equivalent to the rather differently oriented hinges found in most other taxa (but see also those of Sinocalycanthus - parallelism?), hinged anthers may be a synapomorphy for the order, and anthers with slits a synapomorphy for crown-group Calycanthaceae. However, the phylogenetic position of Virginianthus has been questioned, and whether it is in Calycanthaceae, sister to Calycanthaceae (e.g. Doyle & Endress 2010), sister to all other Laurales, or not even to be included in Laurales at all is unclear (Eklund 1999; Crepet et al. 2005; Zhou et al. 2006; Doyle & Endress 2007; Doyle et al. 2008b), although the latter idea is least likely. The Australian Lovellea also has disulcate pollen, but phenetic analyses suggest that it may be sister to Laurales minus Calycanthaceae (see below: Dettmann et al. 2010). The rather younger (Turonian, ca 90 million years before present) Jerseyanthus is more certainly Calycanthaceae, and it may even be sister to Calycanthus; it has the distinctive disulcate pollen common in Calycanthaceae (Crepet et al. 2005), and this was suggested as the age of divergence within Calycanthaceae (Crepet et al. 2004). However, Jerseyanthus is remarkable in having flower parts that from the outside are in the sequence petaloid tepal - introrse staminode - extrorse stamen - abaxially curved "petaloid staminode" - pistillode, an arrangement of parts quite unlike that of any other angiosperm, although Staedler et al. (2007) interpret the outer staminode series as being inner tepals.

Genes & Genomes. Isozyme duplication in Calycanthus suggests that this clade shows ancient polyploidy (Soltis & Soltis 1990).

Chemistry, Morphology, etc. The two rings of vascular bundles in the stem are quite distinct from the seedling stage onwards. The leaf is innervated by paired traces (which very soon fuse and form the median petiole bundle) from the inner series of bundles and then two traces from the cortical bundles that form the lateral or wing bundles (Beck et al. 1982), however, I could not see these central paired traces in Chimonanthus (material too much thickened?). Odd teeth are sometimes found on the lamina of Calycanthus virginianus, at least on the plant in my back garden. Calycanthus occidentalis has inverted recurrent vascular bundles in the hypanthium, perhaps evidence of receptacular epigyny (Dengler 1972). Staedler et al. (2007a) note that the numbers of floral parts, tepals, stamens, staminodes, etc., are more or less Fibonacci numbers (3, 5, 8, 13,....). The carpels in general are more or less plicate. The ovules of Calycanthus are close to tenuinucellate, but with a nucellar cap (Dahlgren 1927) and the micropyle is bistomal (Yamada et al. 2003). There is no triple fusion during fertilisation, and the endosperm develops autonomously. The seeds are poisonous and have characteristic alkaloids.

In morphology and anatomy, Idiospermum is similar to Calycanthaceae s. str., although the alkaloids and the distribution of xylem parenchyma differ in detail. For the morphology of Idiospermum, see Blake (1972), for chemistry, see Crawford et al. (1986).

For general information, see Nicely (1965) and Kubitzki (1993b), for the chloroplast genome, etc., see Goremykin et al. (2003b), for disulcate pollen of Calycanthus, see Albert et al. (2011), for floral development, see Rauh and Reznik (1951), for gynoecial development, see Staedler et al. (2007b), and for floral development in general, with suggestions of apomorphies for the two subfamilies in addition to those suggested above, see Staedler et al. (2009).

Phylogeny. Li et al. (2004) clarify phylogenetic relationships in the family; Idiospermum is sister to the rest.

Classification. Although Idiospermum is a very distinctive genus and has sometimes been recognised as a separate family (e.g. Cronquist 1981), it is monotypic and shares many features with the rest of the family.

[[Siparunaceae [Atherospermataceae + Gomortegaceae]] [Monimiaceae + Hernandiaceae + Lauraceae]]: evergreen trees; vessel elements with scalariform perforation plates; hippocrepiform sclereids in pericycle; mucilage cells + [this level; lamina with rather distant teeth, one vein entering opaque, persistent glandular cap; flowers rather small; A whorled, stamens with paired nectaries/glands at base, anthers bisporangiate/monothecal, valvate, valves apically hinged; tapetum ?; pollen inaperturate, ± spinulose; ovule 1/carpel, median, on early-initiated cross-zone, vascular bundle not branching in chalaza; (fruit with fleshy hypanthium/receptacle; hypanthium splitting irregularly).

Evolution. Divergence & Distribution. Fossils have been used to estimate the age of this clade as ca 91 million years (Crepet et al. 2004: note topology within it). Fossils of Lovellea wintonensis from the upper Albian of Queensland, Australia, have characters suggesting Laurales, although they do not suggest any particular family; morphological cladistic analyses place it somewhere around here (Dettmann et al. 2010). It has disulcate pollen, lacks staminodes, it has an inferior ovary, partly fused carpels with long styluli, the ovule has a hypostase, and the seed has two layers of cells, the inner being made up of transfer cells, each including a crystal (Dettmann et al. 2010). Dettmann et al. (2010) compare Lovellea wintonensis most closely with Gomortega (Gomortegaceae) and Tambourissa (Monimiaceae), i.e. taxa on both branches of this clade.

Chemistry, Morphology, etc. Leitão et al. (1999) summarize alkaloid distribution in Monimiaceae in the old sense, which includes Atherospermataceae, Monimiaceae s. str., Siparunaceae and sometimes even Hernandiaceae. See Doyle (2007) for monimioid leaf teeth in this clade. Staedler and Endress (2009) discuss floral phyllotaxis; there is considerable variation, with whorled and spiral phyllotaxis occurring in all families that are not monotypic and phyllotaxis even varying within a species. There is also considerable variation in exine structure in this part of the tree, the pollen of many taxa having an infratectum that is more or less intermediate between granular and columellar (Doyle 2009).

There is little information on tapetal development, or of most other embryological details and of seed anatomy in this part of the tree; this is especially true of the first three families (see Kimoto & Tobe 2001 for a summary; Bello et al. 2002a for Siparuna). For information on Monimiaceae and the other families previously included in them, see Schodde (1970), Philipson (1993), Sampson (1993, 1997, 2007) and Foreman and Sampson (1987: pollen), Romanov et al. (2007: fruit anatomy) and Kimoto and Tobe (2008b: embryology).

[Siparunaceae [Gomortegaceae + Atherospermataceae]]: acicular crystals +; hypanthium closed by roof; pollen with columellar infratectum; embryo very small.

SIPARUNACEAE Schodde   Back to Laurales

Also lianes; plants Al accumulators; indumentum often stellate; vessel elements also with simple perforation plates; no hippocrepiform sclereids in pericycle; sieve tube plastids?; primary stem?; nodes 1:1; petiole bundles flattened-annular, (medullar plate +); cuticle wax?; lamina vernation curved-conduplicate, (margins entire); plants monoecious or dioecious, P 4-6(-7) or obscure, calyptrate; A (1-)2-many [e.g. 2 + 2 + 2], paired glands 0, anthers often with one flap, tapetum secretory; G 3-many, occluded by secretion as well, stylulus short; ovule unitegmic, integument 3-4(-5) cells across, hypostase +; megaspore mother cells several, embryo sacs several, starch-rich, elongating [Siparuna]; hypanthium fleshy, splitting, (drupelet with a fleshy appendage [= "stylar aril"]); (seeds bilaterally flattened - Glossostigma), endotegmen with reticulate thickenings; n = 22.

2[list]/75: Siparuna (74). Tropical America (Siparuna), W. Africa (Glossocalyx) (map: S. Renner). [Photo - Flower] [Photo - Fruit]

• Siparunaceae may be recognised by their opposite, serrate, estipulate leaves with rather prominent brochidodromous venation; the wood lacks broad rays and the hairs are often stellate or fasciculate. The anthers lack basal glands.

Evolution. Floral Biology & Seed Dispersal. Dioecy seems to have evolved several times from monoecy in Siparunaceae (Renner & Won 2001). Pollination is by genera of cecidomyid gall midges, which lay eggs mostly in male flowers; the larvae destroy the flower (Feil 1992).

In most taxa the hypanthium splits irregularly when the fruits are ripe, the walls spreading widely and exposing the drupelets inside. The drupelets, and/or their fleshy appendages, differ strikingly in color from the inside of the fruit (see also Monimiaceae). This fleshy appendage is called an aril by Renner and Hausner (1997) and occurs only in dioecious taxa.

Chemistry, Morphology, etc. The ovule is interpreted as having lost its outer integument by Kimoto and Tobe (2003); however, is the single integument better thought of as the outer integument?

General information is taken from Philipson (1993) while details of embryology may be found in Heilborn (1931) and Kimoto and Tobe (2003), floral morphology in Endress (1980c), and of pollen development, etc., in Bello et al. (2002a).

Phylogeny. For phylogenetic relationships in Siparunaceae, see Renner and Won (2001).

[Gomortegaceae + Atherospermataceae]: bud scales +; sieve tube plastids also with proteinaceous fibrils; outer A staminodial, inner A not staminodial; style short.

Chemistry, Morphology, etc. Doweld (2001b) emphasized the similarities between Atherospermataceae and Gomortegaceae, especially the tracheoidal endotesta. Both have fruits in which the seed coat would be expected to have lost its protective function.

GOMORTEGACEAE Reiche   Back to Laurales

Alkaloids?; primary stem with separate bundles; nodes 1:2; secondary phloem with flaring rays; cuticle wax?; lamina entire; flower parts between spiral and whorled, hypanthium 0; P 5-7(-9), A 7-13, filaments rather slender; microsporogenesis modified simultaneous; G [2-3(-5)], inferior, stigmatic branches erect, extragynoecial compitum?; ovule apical, hemianatropous [or straight?], apotropous; megaspore mother cell 1; fruit drupaceous; seed single, pachychalazal; embryo large; n = 21.

1/1: Gomortega keule. C. Chile, rare (map: from Donoso Z. 1994). [Photo - Flower]

• Gomortegaceae are aromatic plants with opposite, estipulate, entire leaves. The flowers are small, with staminodes outside the stamens, the ovary is inferior and syncarpous, and the single-seeded fruit is drupaceous.

Chemistry, Morphology, etc. Stern (1955) thought that nodal anatomy was unclear; here I follow Howard (in Metcalfe & Chalk 1987). The inflorescences, often described as being racemose, have a terminal flower. Vessel elements in young wood may have simple perforation plates (Metcalfe & Chalk 1987). Notice that although the body of the ovule is straight, its insertion on the funicle is oblique (cf. Endress & Igersheim 1997).

Some information is taken from Kubitzki (1993b: general), Doweld (2001: seed) and Heo et al. (2004: embryology).

ATHEROSPERMATACEAE R. Brown   Back to Laurales

Bisbenzylisoquinoline alkaloids +; (hairs T-shaped); nodes 1:1; primary stem?; stomata anomocytic; lamina vernation involute [Laurelia] or conduplicate; inflorescence racemose; T = K + C, tapetum plasmodial, pollen polar di- or meridionally syncolpate, reticulate; G 4-many, occluded by secretion as well, (stylulus none); (megaspore mother cell 1); fruit achenial, plumose, hypanthium woody; embryo also medium; n = 22, 57.

6-7[list]/16. New Guinea to New Zealand and New Caledonia, Chile, scattered (map: Renner et al.; Andrew Ford, pers. comm. [Australia]). [Photo - Fruit]

• Atherospermataceae have opposite, coarsely serrate leaves in which the lateral veins join to form a looping vein inside the margin. The flowers are quite small, the hypanthium is dry, and the individual fruitlets are plumose and achenial.

Evolution. Divergence & Distribution. The family is known from forests on the Antarctic Peninsula of the late Cretaceous/early Tertiary, with wood recorded from the Upper Eocene of Germany; the oldest fossils are ca 88 million years ago. An age for the clade as a whole of ca 140 million years has been suggested (Renner et al. 2000).

Chemistry, Morphology, etc. The plants do not accumulate aluminium (Webb 1954). Atherosperma has two sepals completely enclosing the bud, and then eight petals. The vasculature of the anther glands is independent of that of the anthers (Canright 1952).

Some information is taken from Philipson (1993), Endress (1980c: flower), and Stanstrup et al. (2010: chemistry); for wood anatomy (and that of Monimiaceae) see Poole and Gottwald (2001).

Phylogeny. Renner et al. (2000) suggest that a clade made up of Doryphora and Daphnandra, from the Queensland-New South Wales area of Australia, is sister to the rest of the family.

[Monimiaceae [Hernandiaceae + Lauraceae]]: aporphine alkaloids and variants +; (plants Al accumulators); (cork cambium outer cortical); crystals +, small; A whorled; pollen columellae foot layer and endexine 0; ovule apical, pendent, curved 360^o, (micropyle bistomal).

Evolution. Divergence & Distribution. The distinctive Mauldinia (see below under Lauraceae) has been placed sister to this clade in a constrained morphological analysis by Doyle and Endress (2010) - this would date crown group diversification to something under 113 million years ago [incorrect: it has nothing to do with the age of diversification]. Note that it has been suggested that diversification within Monimiaceae began some 20 million years or more after that within Hernandiaceae (cf. Renner et al. 2010 [Monimiaceae] and Michlak et al. 2010 [Hernandiaceae]).

Chemistry, Morphology, etc. See Kimoto and Tobe (2008a) for a comprehensive summary of the variation in embryology and seed of the whole group.

MONIMIACEAE Jussieu   Back to Laurales

Also shrubs or lianes; (plants Al accumulators); primary stem with cylinder or separate bundles; (vessel elements with simple perforation plates); wood with broad rays; nodes 1:1-7; secondary phloem often with flaring rays; sieve tubes with rosette-like non-dispersive protein bodies; (sieve tube plastids also with filaments; starch alone); cuticle wax?; (stomata anomocytic); lamina vernation conduplicate, (margins entire); plants monoecious or dioecious, (flowers perfect - Hortonia); flowers medium-sized, (hypanthium closed by roof); P 3-many, (much reduced), sepaloid, petaloid or calyptrate; A 3-many, paired nectaries 0 (+ - Hortonia, Peumus, Mollinedia; filaments rather slender, connective produced; staminodes + - Hortonia, Peumus), anthers tetrasporangiate, dehiscing longitudinally, (annular), (bisporangiate, dehiscing tranversely - Monimia); tapetum secretory [Peumus]; (pollen grains with encircling aperture); G (1-few)-many, occluded by secretion as well, stylulus short (long - Palmeria), stigma stout, dry; outer integument 2-4 cells across, inner integument 2-3 cells across, hypostase +, funicle stout, obturator + (0); hypanthium fleshy (and splitting) or not, fruit drupelets, (with fleshy appendages); mesotesta usu. tracheidal, (endotesta not tracheidal); embryo short to quite long; n = (18-)19(-22, 39, 43, 57, etc.).

22[list]/200: Mollinedia (90 [?20 - S. Renner, pers. comm.]), Tambourissa (45), Kibara (45). Tropical, but esp. Australasia; fossil wood from the Campanian in Antarctica, etc. (map: Renner et al. 2010, fossil localities in green). [Photo: Fruit, Flower, Fruit, Levieria fruit, Wilkiea fruit].

• Monimiaceae are recognisable by their opposite, rather distantly serrate leaves which have prominent venation on the lower surface with the veins looping and joining near the margin, and their twigs, which have broad rays and are often flattened below the somewhat swollen nodes; some taxa have "laticiferous threads" (Keller 1996). In fruit, the well-developed fleshy hypanthium and/or receptacle is conspicuous; this may enclose the drupelets and it then splits irregularly.

Evolution. Divergence & Distribution. Wikström et al. (2001) date diversification within the clade to (96-)78(-70) million years ago; Renner et al. (2010) suggest that crown Monimiaceae are (93-)90(-87) million years old (there is an 85 million year old fossil), with diversification between Hortonia and the rest (85-)71(-57) million years ago (95% HPD values); dates in Michalak et al. are 80-40 million years, depending on the clock. The separation of Monimia from its sister genus, the East Malesian Palmeria dates to (48-)32(-16) million years, although the former is endemic to the Mascarenes, which are a mere 15-8 million years old (Renner et al. 2010).

Floral Biology & Seed Dispersal. A hyperstigma or an extragynoecial compitum may be present, the pollen germinating on a mucilaginous secretion are the entrance of the hypanthium (Endress 1980c; Friis & Endress 1990). The drupelets are surrounded by a fleshy, accrescent hypanthium. This may split, as in Palmeria, and the colour of the inside forms a striking contrast with that of the drupelets.

Chemistry, Morphology, etc. The pollen of Hortonia is remarkable: it has hollow, spiral sexinous strands and the intine is thick, with tangential channels. Decaryodendron has flowers with up to 1000 carpels, and flowers of Tambourissa have up to 2000 carpels; Mollinedia has carpels that are initially unsealed, but are later occluded by secretion; it also has a whorled perianth. Kibaropsis has four cotyledons.

For floral development, seee Endress (1980b - Hortonia neither a notable intermediate nor archaic, 1980c), for wood anatomy (and that of Atherospermataceae) see Poole and Gottwald (2001), and for fruit anatomy, see Romanov et al. (2007).

Phylogeny. Palmeria, Peumus, and Monimia together form a clade that is sister to the rest of the family (Renner 2002 and references); note that Monimia has anthers with two sporangia (e.g. von Balthazar et al. 2011). Fruit anatomy correlates quite well with phylogeny, e.g., the first three genera have a massively thick endocarp, alone in the family (Romanov et al. 2007).

Previous Relationships. As circumscribed here, Monimiaceae includes only three of the subfamilies, Monimioideae, Hortonioideae and Mollinedioideae, of Monimiaceae as circumscribed by Money et al. (1950), Cronquist (1981), and Takhtajan (1997); for the rest of the family, see Siparunaceae and Atherospermataceae.

Synonymy: Hortoniaceae A. C. Smith

[Hernandiaceae + Lauraceae]: primary stem ± with vascular cylinder; vessel elements with simple perforation plates; sieve tube plastids also with starch; hippocrepiform cells in pericycle?; leaves spiral, lamina margins entire, (lobed); P whorled; (filaments slender); tapetum amoeboid; exine thin, spines set in a reduced granular layer, intine very thick, outer layer with a radially oriented microfibrillar structure; G 1 [thus no extragynoecial compitum], stylar canal 0, stigma dry; ovule pachychalazal, outer integument ³4 cells across, (micropyle not covered), hypostase 0; embryo sac more or less linear; testa thick, multiplicative; endosperm 0; germination epigeal.

Evolution. Divergence & Distribution. The fossil Mauldinia may belong somewhere here, rather than within Lauraceae (Doyle & Endress 2007). Bandulskaia, from the Early Eocene of Tasmania and identified as Lauraceae based on several distinctive epidermal features, has huge leaf teeth 2000+ µm long that lack the glandular cap of teeth of other Laurales; if the fossil is correctly identified, independent origin of these teeth is likely (Carpenter et al. 2007). Cohongarootonia (it has a hollow style) and perhaps Powhatania, both from Early-Middle Albian sediments 125-118 million years old in Virginia are also probably to be placed in this general area (von Balthazar et al. 2011).

Floral Biology. Rohwer (2009) compares the heterodichogamous flowers of Lauraceae with those of Hernandiaceae and suggests that heterodichogamy may be common to the two; he interprets the floral morphology of Hernandiaceae in the context of this idea - heterodichogamy may thus be a synapomorphy at this level. For heterodichogamy in Hernandia, see Endress and Lorence (2004), and for additional possible synapomorphies, see Doyle and Endress (2000). Another scenario for ovary evolution is that it became inferior in the common ancester of Hernandiaceae and Lauraceae, persisting in the latter family in in Hyphodaphnis but subsequently becoming lost - both require two steps (two gains, versus gain and subsequent loss).

Chemistry, Morphology, etc. For the distinctive pollen of these two families, see Kubitzki (1981).

HERNANDIACEAE Blume   Back to Laurales

Trees or lianes; hippocrepiform sclereids in pericycle?; nodes 1:3-9; petiole bundles horizontally [Valvanthera] or vertically elliptic; (stomata anomocytic); branching from previous flush; lamina venation ± palmate; breeding system very variable; flowers (3-)4-5-merous; P 3-10; A 3-5(-7), (nectaries outside A, or 0, or highly reduced), ovary inferior, usu. facing abaxially, stigma peltate; ovule micropyle variable, endostome lobed, outer integument 9-23 cells across, inner integument 3-8 cells across; fruit dry, (a samara).

5[list]/55 - two subfamilies below. Pantropical.

1. Hernandioideae

Al accumulation?; glandular hairs in leaf epidermis; inflorescence thyrsoid; anther valves laterally hinged; tapetal cells radially elongated; single layer of microspore mother cells, pollen grains 90-160 µm across; nucellus massive, parietal tissue 6-8 layers thick, nucellar beak +; bracteoles accrescent in fruit [not Illigera]; (seeds ruminate - usu. Hernandia), testa vascularized, spongy, tanniniferous, walls unthickened, mesotesta massive, 7-17 cells across; n = 18, 20.

3/44. Tropical, esp. Madagascar and Indo-Malesia (map: from Kubitzki 1969; van Balgooy 1975). [Photo - Hernandia Flower, Fruit, Illigera Flower, Fruit.]

Synonymy: Illigeraceae Blume

2. Gyrocarpoideae Pax

Leaves with cystoliths, strong higher-order vein areolation; inflorescence dichasial, ebracteate; flowers very small, P uniseriate, pollen grains 19-45 µm across, nucellar cap +, apical part of embryo sac protruding; cotyledons contortuplicate [much folded!]; n = 15.

2/10. Pantropical, esp. America (map: Kubitzki 1969; van Balgooy 1975).

Synonymy: Gyrocarpaceae Dumortier

• Given the variation in life form and vegetative and fruit morphology in Hernandiaceae, this is not an easy family to recognise. Illigera (Hernandioideae) is a climber with palmately compound leaves and sensitive petioles that can even be mistaken for the monocot Dioscorea, Sparattanthelium (Gyrocarpoideae) is a climber with recurved stem hooks, while Hernandia itself is a tree.

Evolution. Divergence & Distribution. Stem Hernandiaceae are ca (102-)97(-92) million years old (Wikström et al. 2001). However, Michlak et al. 2010) suggest that crown-group diversification began (130-)112-108(-89) million years ago, and there has been widespread dispersal subsequently.

Chemistry, Morphology, etc. Some 128 alkaloids assignable to 17 different structural types have been found in the family; about half of them are aporphine alkaloids (Conserva et al. 2005; see also J.-J. Chen et al. 2011). They show no obvious correlation with phylogeny.

For floral morphology in Hernandia, see Endress and Lorence (2004); see Heo and Tobe (1995) for embryology, etc., and Kimoto and Tobe (2008) for more embryology and nice summary. Some information is also taken from Kubitzki (1969, 1993b).

LAURACEAE Jussieu   Back to Laurales

Flavones, 5-O-methyl flavonols, polyketides [acetogenins], (tryptamine alkaloids) +, (plants Al-accumulators); (cork pericyclic - Cinnamomum; vessel elements with scalariform perforation plates; wood often fluorescing; (secondary phloem stratified); nodes 1:2 (1:3); also crystals and crystal sand +; (stomata anomocytic); bud scales + (0); branching from current flush; leaves (opposite), lamina often glaucous below, vernation conduplicate or supervolute, higher-order vein areolation stong; plants heterodichogamous (polygamous to dioecious); inflorescence umbellate to thyrsoid; (flowers 2-merous - Potameia), hypanthium often short, T 3 + 3 (2 + 2; K + C); A 3 [introrse] + 3 [often introrse] + 3 [extrorse; with glands] 1 whorl staminodial (4-several whorls of stamens; when dioecious, 3 whorls of staminodes in male plants, the third whorl of stamens=staminodes in female plants), sporangia widely separated; microspore mother cells in single row, (microsporogenesis simultaneous); (pollen monosulcate); (stylulus 0), stigma also capitate; outer integument 3-5(-11) cells across, inner integument 2-4 cells across; megaspore mother cells usu. 1; fruit a drupelet [endocarp palisade], pedicels (and tepals) often thickened and colored; (seed ruminate), testa vascularized or not, often multiplicative, (exotestal cells cubicendotestal cells longitudinally or transversely elongated; endosperm nuclear; n = (11-)12 (15 - Eusideroxylon, Endiandra), chromosomes 1-5(-7 - Cassytha) µm long.

1. Hypodaphnis

Anthers tetrasporangiate; glandular tapetum?; staminodes 0; G inferior.

1/1: Hypodaphnis zenkeri. Tropical West Africa.

[[Beilschmiedia, Cryptocarya, Endiandra, etc.] [Cassytha [Caryodaphnopsis and Neocinnamomum + The Rest]]]: subsidiary cells of paracytic stomata envelop the guard cell both above and below, the guard cells having outer and inner cuticular ledges; staminodes +, glandular tapetum +; ovary superior to inferior; embryo sac protruding from nucellus: fruit type?

2. Beilschmiedia, Cryptocarya, Endiandra, etc.

Stamens in two whorls (three whorls, many); (G inferior); fruit a berry.

6/710: Cryptocarya (350), Beilschmiedia (250), Endiandra (80). Pantropical, some subtropical, to New Zealand.

[Cassytha [Caryodaphnopsis and Neocinnamomum + The Rest]]

3. Cassytha

Parasitic herb; micropyle bistomal, nucellar cap 0, pachychalaza 0; endosperm cellular.

1/16. Tropics, warm temperate in Australia - see The Parasitic Plant Collection.

Synonymy: Cassythaceae Lindley, nom. cons.

Caryodaphnopsis and Neocinnamomum + The Rest: ?

Caryodaphnopsis + Neocinnamomum

Anthers tetrasporangiate.

2/21. Central and South America, South East Asia to the Philippines and Borneo.

5. The Rest

(Plant deciduous); (paired nectaries/glands 0 - Mezilaurus clade); tapetum amoeboid; embryo sac not protruding.

Ca 40/1730: Ocotea (350), Litsea (?400), Persea (200), Cinnamomum (350: cinnamon), Lindera (100). Pantropical (temperate).

Synonymy: Perseaceae Horaninow

• The family may be recognised by its aromatic smell, nearly always entire spiral or opposite (very rarely two-ranked) quite long-petiolate leaves the blades of which are often quite thick (they are coriaceous when dry) and with a glaucous undersurface and rather steeply ascending secondary veins. The bark oxides on exposure. The twigs are often more or less ridged, the ridges being decurent from the bases of the petioles, and branching is often on the current flush - even in temperate taxa there is often a mixture of proleptic and sylleptic branching on the same plant. The flowers are small, trimerous, and have valvate anthers; the fruit has a single, large seed that lacks endosperm and the pedicel - and sometimes also tepals and hypanthium - is often ± swollen and conspicuous. Some Lauraceae have a growth pattern similar to that of Myristicaceae, with whorled branches and periodic growth, but the leaves on the branches of Lauraceae are usually spiral, rarely opposite, while in Myristicaceae (and Annonaceae) the leaves are nearly always distichous.

Evolution. Divergence & Distribution. Chanderbali et al. (2001) suggest an age of 174 ± 32 million years before present for the family, but its diversification may have occurred only (93-)61(-26) million years ago (Michalak et al. 2010). Note that Labandeira et al. (2002b) assign many fossil leaves from the earliest Tertiary of North America to extant genera of Lauraceae.

Lauraceae are prominent in Mid to Late Cretaceous floras, and include the Early Cenomanian Mauldinia which is ca 100 million years old (Drinnan et al. 1990; Viehofen et al. 2008). Mauldinia has remarkable inflorescences in which the lateral units are flattened and bilobed, bearing sessile flowers on their adaxial surfaces; these flowers are very like those of extant members of the family (see also Crepet et al. 2004; Friis et al. 2006b for references), and the fossil has been used to date the family (Crepet et al. 2004 - but see above). The distichous bracts/prophylls of these inflorescence units is a distinctly odd feature in the family. Recently a flower provisionally assigned to Lauraceae, although with a unusual combination of floral characters - there are only two whorls of stamens and no nectaries/glands - has been described from deposits in Virginia some 112-105 million years old (von Balthazar et al. 2007). The Upper Cretaceous Marmarthia has leaf blades with palmate venation; the margins are lobed or perhaps toothed... (Peppe et al. 2007).

A better understanding of biogeographic relationships will depend on a more complete phylogeny, but it is interesting that the Macaronesia Persea indica is part of a New World clade - and sister (but with rather poor support) to this clade is another Macaronesian member of the family, Apollonias barbujana (Rohwer et al. 2009). Diversification in the speciose New World Ocotea is likely to have been rather recent (Renner 2005a).

Ecology & Physiology. The family is prominent in the lowland tropical rainforests of South East Asia-Malesia and America in particular, and in tropical montane forests in the latter it may be the most speciose family (Gentry 1988).

Floral Biology & Seed Dispersal. The basic mode of flowering in the family may be heterodichogamy or dianthesis. Plants are of two types, and one plant will be in the staminate phase while the other is in the carpellate phase, and vice versa. The staminodes produce nectar when the plant/flower is in the carpellate phase and the staminal glands of the third staminal whorl produce nectar when the plant/flower is in the staminate phase (Rohwer 2009, see also above).

Dispersal of the fruits is by animals.

Chemistry, Morphology, etc. Lindera, at least, has distinctive C₁₀, C₁₂ and C₁₄ monounsaturated fatty acids in its seeds (Badami & Patil 1981). Vestured pits are apparently absent; rays alone may be storied (Metcalfe 1987: P. van Rijckevorsel [pers. comm.] clarified reports of vestured pits and wood storying in the family). Distinctive paracytic stomata in which the subsidiary cells almost envelop the very small guard cells, the latter having outer and inner cuticular ledges, may be an apomorphy for all Lauraceae except Hyphodaphnis (Carpenter et al. 2007), however, Nishida and van der Werff (2007) found more conventional stomata in at least some Lauraceae other than Mezilaurus (for stomata, see also Hill 1986). Indeed, from a surface view it may seem as if the stomata are anomocytic, the guard cells being totally obscured.

It has been suggested, largely on the basis of gene expression, that the perianth in some Lauraceae - Persea, at least - may represent modified stamens (Chanderbali et al. 2004, 2006). Both the tepals and the stamens of Persea have three traces (Reece 1939: the ovule is reported to be anatropous!). However, other reports suggest that the stamens have single traces, even if both whorls of tepals have three traces (Laurus) or often one trace in the inner whorl alone (Umbellularia - see Kasapligil 1951). Clearly more work is needed here. Multistaminate Lauraceae attain this condition by the increase in number of the stamen whorls. Dahlgrenodendron has pollen grains with exine, columellae, etc. The orientation of the single carpel varies (Ronse de Craene et al. 2010 and literature). Kimoto et al. (2006) summarize embryological findings in Lauraceae. Variation in the anatomy of the pericarp, development of the cupule in fruit, etc., is summarized by Little et al. (2009). The testa is not always multiplicative. Kasapligil (1951) described a tracheidal endotegmen at the radicular end of the seed. Both isozyme duplication and stomatal size increase over time suggest ancient polyploidy in this clade (Soltis & Soltis 1990; Masterson 1994). Is the base chromosome number 6?

Kimoto et al. (2006) note that a minor change on the tree that they used would mean that a glandular anther tapetum and possibly also protruding embryo sac arose on a single clade and did not reverse; they thought that characters like a glandular tapetum and an embryo sac protruding from the nucellus arose in parallel. However, in the topology suggested by Rohwer and Rudolph (2005: not cited by Kimoto et al. 2006) it appears that these characters are found in all (glandular tapetum) or most (protruding embryo sacs) members that have been examined on three successive branches of the tree, but are not, or only very rarely, found in the Mezilaurus group and other core Lauraceae. This suggests that there may have been reversal/loss of these characters in other Lauraceae; note that protruding embryo sacs are also found in Hernandiaceae-Gyrocarpoideae. I have optimised these and some other characters (especially von Balthazar et al. 2007) in the context of a provisional phylogeny of Lauraceae suggested by Rohwer and Rudolph (2005: see below), but it will be clear that where most of characters might properly be placed on the tree is very uncertain, both because the topology is uncertain and because our basic understanding of the morphological variation is poor.

General information is taken from Rohwer (1993a), some embryological details from Heo et al. (1998) and Endress and Sampson (1983), wood anatomy from Richter (1981) and van Rijckevorsel (2002), fruit anatomy from Heo (199-), stomata from van der Merwe and van Wyk (1994), cuticle from Christophel et al. (1996) and Nishida and van der Werff (2011), cytology from Oginuma et al. (1998), chromosome size from de Moraes et al. (2007), and androecial development from Buzgo et al. (2007).

Phylogeny. Hypodaphnis, with an inferior ovary, is sister to the rest of the family, then Cassytha (but a long branch), then Beilschmeidia + Cryptocarya + Endiandra, then Caryodaphnopsis, then Chlorocardium + Mezilaurus + Williamodendron (Rohwer 2000: matK); for more details, see Chanderbali et al. (2001). There are a number of taxa with long branches, and complex analyses by Rohwer and Rudolph (2005) strongly suggests a slight modification of this set of relationships: Hypodaphnis [[the Cryptocarya group] [Cassytha [[Caryodaphnopsis + Neocinnamomum] [[the Mezilaurus group] [core Lauraceae]]]]] - most of these clades have about 100% posterior probabilities. If this topology is confirmed, it will have considerable implications for character evolution (see above).

Litsea is polyphyletic, although section Litsea is monophyletic, and Lindera is also polyphyletic (Fijridiyanto & Murakami 2009). Note that the recognition of Neolitsea appears to make Actinodaphne paraphyletic (Li et al. 2007), results confirmed in a broader study (Li et al. 2008). For relationships in the Persea area, see Rohwer et al. (2009); Phoebe and Persea are para/polyphyletic, while the relationships of the Macaronesian Persea indica and perhaps Apollonias barbujana are with New World clades.

Classification. The genera are very difficult to recognise without flowers and are rather unsatisfactory even with them, often being based on single character differences in the androecium, such as sporangium number and direction of sporangium opening. However, both extrorse and introrse anthers can occur in the same flower, although the extrorse condition seems to be developmentally derived (Buzgo et al. 2007), thecae may be 2 or 4, their arrangement on the broad connective varies, etc. (e.g. Kopp 1966; Rohwer et al. 1991; Rohwer 1993, 1994a; van der Werff & Richter 1997); substantial changes in generic limits are to be expected.