Pearsonia Dümmer

First published in J. Bot. 50: 353 (1912)
This genus is accepted
The native range of this genus is Tanzania to S. Africa, Madagascar.

Descriptions

Legumes of the World. Edited by G. Lewis, B. Schrire, B. MacKinder & M. Lock. Royal Botanic Gardens, Kew. (2005)

Note

The current state of knowledge of the Crotalarieae was reviewed by Van Wyk (1991a) and by Van Wyk & Schutte (1995a). The most conspicuous recent change has been the exclusion of the Argyrolobium group (six genera, i.e. Argyrolobium, Dichilus, Melolobium, Polhillia, Anarthrophyllum and Sellocharis), which belong in tribe Genisteae rather than in Crotalarieae, where they were previously placed (Polhill, 1981q: 399 –402). New insights into relationships within the tribe have come mainly from chemosystematic studies of alkaloids (summarised in Van Wyk & Verdoorn, 1990) and several recent generic monographs (see below).

The Crotalarieae forms part of a monophyletic clade, the ‘core genistoids’ (Fig. 36) which also includes Genisteae, Podalyrieae, Thermopsideae, Brongniartieae, Euchresteae and Sophoreae sens. strict. (Crisp et al., 2000; Pennington et al., 2000a; Kajita et al., 2001). Crotalarieae appears to be sister to the Genisteae and both are sister to the Podalyrieae (Crisp et al., 2000; Wojciechowski et al., 2004). This clade is in turn sister to the Thermopsideae and Sophoreae sens. strict. (including Euchresteae).

The Crotalarieae shares with the Podalyrieae the absence of a-pyridone alkaloids such as cytisine and anagyrine that are a typical feature of all other ‘core genistoid’ tribes. Despite a lack of defining characters, the monophyly of the tribe as circumscribed here is well supported by molecular evidence (Crisp et al., 2000; Wink & Mohamed, 2003) and by cladistic analyses of morphological, cytological and chemical characters (Van Wyk & Schutte, 1995a). The latter study suggested an early diversification of the genera with uniform anthers and lupanine-type esters of quinolizidine alkaloids (Pearsonia, Rothia and Robynsiophyton) followed by the poorly known Spartidium and then the so-called ‘Cape group of genera’ (Polhill, 1981q: 399–402), which now includes Lotononis and Crotalaria. Relationships between the seven genera of the ‘Cape group’ remains unresolved despite several recent molecular studies because sampling is still relatively poor. However, a basally branching position in the tribe of the ‘Cape group’, notably Lebeckia and Wiborgia — as considered by Polhill (1976, 1981q) — is now accepted here. The exclusion of the Argyrolobium group, based on morphological and chemical characters, is also strongly supported by DNA sequence data. Due to reticulate and overlapping patterns of character state distribution in the Crotalarieae sens. strict., generic delimitations are intricate and subject to misinterpretation. Several of the large and diverse genera appear to be either monophyletic or paraphyletic depending on the choice of characters. As currently circumscribed the tribe includes 11 genera and c. 1204 species (Fig. 37).

Morphologically similar to Lotononis (particularly in the lotononoid calyx) but distinctive in the gullet-type pollination mechanism and the accumulation of unique esters of quinolizidine alkaloids, two features shared only by Rothia and Robynsiophyton (Van Wyk & Verdoorn, 1991)
Habit
Shrublets and herbs
Ecology
Seasonally dry tropical to subtropical montane xerophytic bushland, shrubland and grassland, sometimes in forest or woodland; on sand or rocky outcrops
Distribution
Africa and Madagascar (12 spp. in Africa S of the equator, mainly in the southern Afromontane Region [Drakensberg and Inyangani Centres], and 1 sp. in Madagascar)
[LOWO]

Leguminosae, various authors. Flora Zambesiaca 3:7. 2003

Morphology General Habit
Perennial herbs or small shrubs.
Morphology Leaves
Leaves digitately 3-foliolate; stipules linear to foliaceous or lacking.
Morphology Reproductive morphology Inflorescences
Inflorescences terminal or leaf-opposed, the flowers in racemes or solitary on long peduncles, sometimes resupinate; bract and bracteoles linear to elliptic-obovate.
Morphology Reproductive morphology Flowers Calyx
Calyx not or slightly inflated; lobes rarely subequal, usually with the upper sinuses slightly to much shallower than the lower sinuses, the lateral sinuses sometimes the shallowest, the lowest lobe narrower than the others.
Morphology Reproductive morphology Flowers Corolla
Standard yellow or white marked purplish, generally elliptic to oblong-obovate, concave in the lower part, usually hairy outside; wings broadened upwards, generally sculptured; keel relatively small, narrow, long-clawed, usually pointed with a small forwardly directed tip.
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens in a sheath open on the upper side and not much longer than the free parts, the vexillary filament sometimes free; anthers narrowly oblong, subequal, but 6 (including the carinal one) attached higher up.
Morphology Reproductive morphology Flowers Gynoecium Style
Style nearly straight or pointed downwards.
Morphology Reproductive morphology Fruits
Pods sessile, linear-oblong to ellipsoid, pointed, laterally compressed, dehiscent, 1–many-seeded.
Morphology Reproductive morphology Seeds
Seeds ± oblique-cordiform, with a small hilum.
[FZ]

Leguminosae, J. B. Gillett, R. M. Polhill & B. Verdcourt. Flora of Tropical East Africa. 1971

Morphology General Habit
Perennial herb
Morphology Leaves
Leaves digitately 3-foliolate
Morphology Leaves Stipules
Stipules similar to the leaflets, in pairs
Morphology Reproductive morphology Inflorescences
Inflorescence terminal, sometimes leaf-opposed, pedunculate, racemose, few-flowered; bracts and bracteoles inconspicuous
Morphology Reproductive morphology Flowers Calyx
Calyx-lobes acute, with the upper 2 united farther up than the lower ones
Morphology Reproductive morphology Flowers Corolla
Standard ovate or elliptic, with a short claw; wings as long as the standard; keel much shorter, rounded at the apex
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens of unequal length (see fig. 116), 9 united, 1 free; anthers uniform
Morphology Reproductive morphology Flowers Gynoecium Pistil
Ovary sessile, with numerous ovules; style curved downwards; stigma small, capitate
Morphology Reproductive morphology Fruits
Pod oblong, slightly inflated
Morphology Reproductive morphology Seeds
Seeds numerous.
[FTEA]

Sources

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Legumes of the World Online

    • http://creativecommons.org/licenses/by-nc-sa/3.0