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Flora of the Venezuelan Guayana

<< Flora Home

ANNONACEAE

by Julian A. Steyermark, Paul J. M. Maas, Paul E. Berry, David M. Johnson, Nancy A. Murray, and Heimo Rainer

Trees, shrubs, or lianas (lianas rare in the Neotropics). Leaves simple, alternate, usually distichous, pinnately veined, glabrous or pubescent with simple or stellate hairs or peltate scales, exstipulate; margins entire. Inflorescence leaf-opposed, internodal, or axillary; cauliflory and flagelliflory (flowers on long runners from base of trunk) also occur. Flowers solitary, in fascicles, or in modified cymose inflorescences (rhipidia), bisexual or infrequently unisexual (plants then androdioecious). Sepals 3, rarely 2 or 4, distinct or ± connate, valvate or imbricate; petals usually 6, arranged in 2 whorls of 3, sometimes only 3, rarely 8, in some Old World species 4, 5, or 7--10, valvate or imbricate. Stamens numerous and spirally arranged or less frequently in low numbers and whorled, staminodes present in some genera; filaments usually short, generally distinct or rarely connate at base into a short tube; anthers 2-locular, latrorse or extrorse, opening longitudinally mostly by valves, the locules sometimes divided by transverse membranes into a row of smaller chambers (locellate); apex of anther connective usually expanded above the locules, often shield-like. Carpels numerous, rarely 1; ovules 1--many per carpel, attached basally, laterally, or apically. Fruit usually of separate, stipitate, fleshy, indehiscent monocarps, sometimes dry and/or dehiscent, or the carpels coalescent to form an aggregate fruit. Seeds arillate or not; endosperm copious, ruminate, usually oily; embryo minute.

Pantropics, with a temperate extension into eastern North America; 130 genera and ca. 2000 species, 17 genera and 102 species in the flora area.

Other genera expected to occur in the flora area but not yet collected there include Cremastosperma, Duckeanthus, Malmea, and Trigynaea. Cremastosperma is characterized by axillary flowers, with the bract above the pedicel articulation, and an apical seed attachment in 1-seeded, stipitate monocarps; its leaves have the midrib distinctly raised and becoming broader towards the base. Duckeanthus can be recognized by its pseudosyncarpous fruits and nonaxillary flowers (like Duguetia) and by its leaf midvein raised on the upper side (sunken in Duguetia). Malmea is recognized by its mostly nonaxillary flowers, thin petals with ciliate margins and turning blackish when dry, the receptacle often woody, and fruits composed of many, free, 1-seeded monocarps. Finally, Trigynaea has leaves that are often tripliveined at the base, flowers that are supra-axillary and ebracteate, and fruits composed of 1 or 2 thick-walled, many-seeded, hairy monocarps; the seeds are trigonous and have a large rudimentary aril.

Key to the Genera of Annonaceae
by Paul J. M. Maas

1. Leaves spirally arranged; flowers 4-merous; indument of stellate hairs; monocarps 1- or 2-seeded, thick-walled (1--4 mm thick)...15. Tetrameranthus

1. Leaves arranged in 2 rows along the stems (distichous); flowers 3-merous; indument of various types (stellate, scale-like, or simple hairs) or lacking; monocarps 1- or more-seeded, thin- or thick-walled, or fruits pseudosyncarpous...2

2(1). Indument of stellate and/or scale-like hairs; fruits pseudosyncarpous (monocarps strongly coherent, but only partly connate), the lower carpels sterile and forming a basal collar...6. Duguetia

2. Indument of simple hairs or lacking (hairs occasionally stellate in Annona, and microscopic stellate hairs occur in Anaxagorea); fruits either syncarpous or apocarpous, but not as above...3

3(2). Flowers and fruits terminal, leaf-opposed, or supra-axillary (not axillary), rarely cauliflorous in some species of Annona; fruits syncarpous (except apocarpous in Cymbopetalum)...4

3. Flowers and fruits axillary (sometimes leaf-opposed in Anaxagorea brevipes) or cauliflorous; fruits apocarpous (with distinct monocarps)...7

4(3). Bracts absent; fruits apocarpous; monocarps many-seeded, constricted between the seeds, dehiscent; flowers pendent on pedicels to 14 cm long; inner petals boat-shaped...4. Cymbopetalum

4. Bracts present; fruits syncarpous; flowers usually on shorter pedicels than above; inner petals not boat-shaped...55(4). Outer petals winged, green to yellow...14. Rollinia

5. Outer petals not winged, green, white, yellow, or red...6

6(5). Flowers with staminodes between petals and stamens; fruit with a distinct basal woody collar; leaves with a distinct marginal vein...8. Fusaea

6. Flowers with stamens all fertile; fruit sometimes with persistent sepals but never with a basal woody collar; secondary veins, if joining, not forming a distinct marginal vein...2. Annona

7(3). Leaf midvein raised on the upper surface...8

7. Leaf midvein flat or impressed on the upper surface...13

8(7). Pedicels with 3 or more bracts; flowers white, £ 10 mm long; monocarps 1-seeded...11. Oxandra

8. Pedicels with 1 or 2 bracts; flower color and size various; monocarps with 1 or more seeds...9

9(8). Marginal leaf vein usually < 3 mm from the margin...13. Pseudoxandra

9. Marginal leaf vein, when present, more distant from the margin...10

10(9). Base of leaf blades asymmetrical; inflorescences many-flowered; flowers £ 5 mm long; monocarps very short-stipitate, 1-seeded...3. Bocageopsis

10. Base of leaf blades symmetrical; without the above combination of flower and fruit characters...11

11(10). Leaves with the lower order reticulate venation raised and conspic-uous on both surfaces; monocarps 1-seeded; seeds 25--30 mm long...12. Pseudephedranthus

11. Leaves with the lower order reticulate venation not raised, inconspic-uous; monocarps (1)2- or more-seeded; seeds much smaller than above...12

12(11). Secondary veins of the leaves flat on the upper surface (except Anaxagorea brevipes); monocarps 2-seeded, dolabriform (hatchet- or golf club-shaped), dehiscent; seeds smooth, shiny; petals fleshy, 2--10 mm thick...1. Anaxagorea

12. Secondary veins of the leaves impressed on the upper surface; monocarps 1--several-seeded, globose to ellipsoid, indehiscent; seeds pitted; petals not fleshy, ca. 1 mm thick...16. Unonopsis

13(7). Pedicels with more than 3 bracts; flowers £ 13 mm long; monocarps 1-seeded...14

13. Pedicels with 1 or 2 bracts; flowers longer than above; monocarps 1--several-seeded...15

14(13). Plants androdioecious (some flowers male only); anthers with ± flattened (discoid) connectives at the tip; monocarps numerous, generally more than 13 per fruit...7. Ephedranthus

14. Plants generally hermaphroditic; anthers with elongate (conical or tongue-shaped) connectives at the tip; monocarps generally fewer than 13 per fruit...11. Oxandra

15(13). Petals fleshy, 2--10 mm thick, often covered with brownish hairs; monocarps explosively dehiscent, dolabriform (hatchet- or golf club-shaped), 2-seeded...1. Anaxagorea

15. Petals generally much thinner; monocarps indehiscent or nonexplosively dehiscent, not shaped as above...16

16(15). Inner petals strap-shaped or linear; ovules and seeds usually more than 1, lateral...17

16. Inner petals broadly lanceolate, ovate, or oblong; ovule and seed solitary, basal...18

17(16). Inner petals 2-glandular at base; some flowers staminate only; monocarps sessile, 3--8-seeded, thick-walled (2--6 mm thick), indehiscent...5. Diclinanona

17. Inner petals lacking basal glands; flowers all bisexual; monocarps stipi-tate, 1--several-seeded, thin-walled, dehiscent...17. Xylopia

18(16). Inner petals about the same size as the outer ones and with a felt-like pad at the base; leaves short-petiolate, the petioles usually < 1 cm long...9. Guatteria

18. Inner petals much larger than the outer ones, lacking a pad at the base; leaves long-petiolate, the petioles usually > 1 cm long...10. Heteropetalum

Scientific Comments:
Paul Berry (peberry@facstaff.wisc.edu) or Kay Yatskievych (kay.yatskievych@mobot.org).

 

 
 
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