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Cruckshanksia Hook. & Arn. (Rubiaceae: Coussareae)

Charlotte M. Taylor [webpage]
Missouri Botanical Garden
P.O. Box 299
St. Louis, MO 63166
 

Click on the images below to see a larger image
Cruckshanksia hymenodon in northern Chile Cruckshanksia pumila in the Atacama Desert of Chile Cruckshanksia pumila in the Atacama Desert of Chile
Cruckshanksia hymenodon in northern Chile

Cruckshanksia pumila in the Atacama Desert of Chile


Cruckshanksia Hook. & Arn. includes seven species of low, hemicryptophytic shrubs and annual herbs found in the Atacama Desert and the Andes of nothern to central Chile and adjacent Argentina. Cruckshanksia can be recognized by its opposite leaves, its interpetiolar stipules that are triangular to bilobed or erose, its flowers borne severally in terminal cymes, its yellow or pink salverform corollas with slender long tubes, and its papery loculicidal capsules. The flowers are diurnal and distylous. The tissue do contain raphides, although these may be difficult to observe.

The leaves and inflorescence bracts of several species of Cruckshanksia may be deeply 2-3-lobed. Several species have one or more calyx lobes on each flower that are expanded into calycophylls (i.e., expanded foliaceous structures), which are petaloid and white to colored in flower and later become papery. In flower these structures presumeably help attract pollinators, while in fruit they apparently aid in dispersal or at least dehiscence of the capsules. The annual species C. pumila grows in regions of the Atacama Desert that only receive rain during El Niño years, thus only for a couple weeks every third to fifth year; its seeds are dormant on the ground between rains. Cruckshanksia hymenodon is the most widely distributed and frequently collected species of this genus.

Cruckshanksia has been confused with another genus of southern South America, Oreopolus Schltdl. However these genera differ in several characters, as summarized in the key presented on the Oreopolus web page. Cruckshanksia and its relationship to Oreopolus have been studied by Ricardi (1963), Ricardi & Quezada (1963), and Taylor (1996). Ricardi (1963) and Ricardi & Quezada (1963) recognized seven species of Cruckshanksia and three of Oreopolus; however Taylor (1996) recognized only seven species of Cruckshanksia, including two of the species that Ricardi & Quezada included in Oreopolus.

Cruckshanksia was previously included in the Hedyotideae by many authors, although Bremekamp and later Anderson & Rova (1999) placed it in the Cruckshanksieae. More recently, based on molecular data Bremer & Manen (2000) transferred both Oreopolus and Cruckshanksia to the neotropical tribe Coussareae. In their expanded circumscription Coussareae comprises a notable range of fruit types, from single- to multi-seeded, fleshy, indehiscent fruits (Coussarea, Coccocypselum) to leathery schizocarps (Declieuxia) and dry multi-seeded capsules (Heterophyllaea); it is not yet clear what morphological features unite the genera now placed in this tribe.

References

  • Andersson, L. & J.H.E. Rova. 1999. The rps16 intron and the phylogeny of the Ruboideae (Rubiaceae). Pl. Syst. Evol. 214: 161-186.
  • Bacigalupo, N.M. 1999. Rubiaceae. In: M. N. Correa, Flora Patagonica Parte 6: 423-443.
  • Bremer, B. & J.-F. Manen. 2000. Phylogeny and classification of the subfamily Rubioideae (Rubiaceae). Pl. Syst. Evol. 225: 43-72.
  • Moore, D.M. 1983. Flora of Tierra del Fuego.
  • Ricardi, M. 1963. Rehabilitación del género Oreopolus Schlecht. Gayana, Bot. 7: 3-7.
  • Ricardi, M. & M. Quezada. 1963. El género Cruckshanksia (Rubiaceae). Gayana, Bot. 9: 3-36.
  • Taylor, C.M. 1996. Taxonomic revision of Cruckshanksia and Oreopolus (Rubiaceae: Hedyotideae). Ann. Missouri Bot. Gard. 83: 461-479.

Key to the Species of Cruckshanksia

1. Calyx lobes equal, none bearing petaloid appendages or all the lobes
bearing them, thecalyx lobes elliptic to oblanceolate or with stipitate, elliptic to ovate petaloid appendages (i.e., calycophylls) in flower, these appendages sometimes becoming orbicular to broadly elliptic in fruit.
2. Leaf blades 15-40 mm long, sharply acute at apex; stipules 1.5-2 mm
long; calyx lobes in flower 10-15 mm long, in fruit 12-23 mm long, without stipes...C. palmae

2. Leaf blades 8-20 mm long, obtuse to rounded at apex; stipules
0.8-1.6 mm long; calyx lobes in flower 3.5-11 mm long (including stipe, when present), in fruit 7-17 mm long, elliptic to oblanceolate, and without stipes, or 10-15 mm long and with stipes.

3. Calyx lobes in flower all composed of stipes 3-6 mm long bearing
elliptic to ovate appendages 3-5 mm long, in fruit the stipes 10-15 mm long with the appendages ovate and 9-13 mm long....C. lithiophila

3. Calyx lobes elliptic to oblanceolate, without stipes, in flower
3.5-5 mm long, in fruit 7-17 mm long...C. macrantha

1. Calyx lobes unequal with 1-4 of them bearing petaloid appendages, these
appendages orbicular to broadly elliptic in flower and fruit, the remaining 1-4 calyx lobes elliptic to narrowly triangular or subulate.
4. Plants annual or perhaps sometimes perennial; corolla lobes 1-2.5 mm
long; corolla tube 0.1-0.3 mm in diameter near its middle...
C. pumila

4. Plants perennial; corolla lobes 2-4.5 mm long; corolla tube 0.3-1 mm
in diameter near its middle.

5. Petaloid calyx lobe appendages pink or white (though frequently
drying yellow); leaves 2-15 mm wide...C. hymenodon

5. Petaloid calyx lobe appendages yellow; leaves 0.8-6 mm wide.
6. Cauline leaves simple or sometimes 3-lobed; petaloid calyx
lobe appendages 6-10 x 8-15 mm in flower, to 12 x 18 mm in fruit... C. montiana

6. Cauline leaves simple to usually 2-3-lobed; petaloid calyx
lobe appendages 3-6 x 2-7 mm in both flower and fruit.....C. verticillata

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List of Names and Synonyms of Cruckshanksia

Accepted names are presented in bold; synonymous names appear with an equals sign. Further information on these names can be found in the TROPICOS database [http://www.tropicos.org/].

Cruckshanksia bustillosii Phil. = Cruckshanksia hymenodon
Cruckshanksia capitata Phil. = Cruckshanksia montiana
Cruckshanksia capitata var. densiflora (Phil.) Reiche = Cruckshanksia montiana
Cruckshanksia chrysantha Phil. = Cruckshanksia pumila
Cruckshanksia darapskyana Phil. = Cruckshanksia pumila
Cruckshanksia densifolia Phil. = Cruckshanksia montiana
Cruckshanksia geisseana Phil. = Cruckshanksia pumila
Cruckshanksia glacialis Poepp. & Endl. = Oreopolus glacialis
Cruckshanksia hymenodon Hook. & Arg., northern to central Chile and adjacent

Argentina, 20-2950 m
Cruckshanksia hymenodon var. bustillosii (Phil.) Ricardi = Cruckshanksia
hymenodon
Cruckshanksia lithiophila Ricardi, Andes of northern Chile, 3300-3600 m
Cruckshanksia macrantha Phil., Andes of northern and central Chile and
Argentina, 1100-4300 m
Cruckshanksia montiana Clos, northern Chile, 10-500 m
Cruckshanksia palmae Clos, Andes of north-central Chile, 2000-4000 m
Cruckshanksia pumila Clos, northern Chile, 10-1900 m
Cruckshanksia tripartita Phil. = Cruckshanksia pumila
Cruckshanksia verticillata Phil., northern Chile, 100-1000 m
Oreopolus macrantha (Phil.) Ricardi = Cruckshanksia macrantha
Oreopolus palmae (Clos) Ricardi = Cruckshanksia palmae

Rotheria lanceolata Meyen = Cruckshanksia hymenodon

Text and Images, unless otherwise indicated, Copyright © by Charlotte M. Taylor. All rights reserved.

This page was revised on April, 2008.

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