Caesalps on southern continents, part 2
Having examined caesalps in Australia, let us turn to South America, where tree-dominated vegetation is most extensively rainforest (see https://www.nature.com/articles/s41598-019-50323-9) but also includes large areas of woodland and savanna.
Caesalps have a far greater incidence In South America than in Australia. However, they are not dominant in the vegetation, with a few exceptions such as Mora (https://en.wikipedia.org/wiki/Mora_(plant)) and Dicymbe (http://www.grupoecologiatropical.com/wp-content/uploads/2016/10/2008-Mycorrhiza-paper-McGuireal.pdf).
Shrubby/weedy genera are common, e.g. Caesalpinia, Senna (which includes trees in South America, https://en.wikipedia.org/wiki/Senna_(plant)), Erythrostemon and Chamaecrista.
Many genera form trees, e.g. Libidibia (https://www.inaturalist.org/observations/95870454), Schizolobium (https://en.wikipedia.org/wiki/Schizolobium_parahyba), Copaifera (https://en.wikipedia.org/wiki/Copaifera), Hymenaea (https://en.wikipedia.org/wiki/Hymenaea), Eperua (https://en.wikipedia.org/wiki/Eperua) and Pterogyne (https://en.wikipedia.org/wiki/Pterogyne). In the case of several species of Tachigali, the trees can reach up to 40 metres.
Caesalps in the form of trees are present in many vegetation types. However, as in Australia, those types of woodland or savanna that are dominated by legumes tend to favour Mimosaceae (e.g. see https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0220151).
Some examples of genera according to the various ecosystems are as follows:
- northernmost rainforests: Mora, Dicymbe (which can be ectomycorrhizal and dominate vegetation), Tachigali, Dialium (https://en.wikipedia.org/wiki/Dialium_guianense)
- amazon forest: Macrolobium (https://en.wikipedia.org/wiki/Macrolobium), Tachigali, Dicymbe, Schizolobium amazonicum, Campsiandra (https://tropical.theferns.info/viewtropical.php?id=Campsiandra+angustifolia and https://en.wikipedia.org/wiki/Campsiandra and https://www.inaturalist.org/observations/96654430)
- caatinga: Bauhinia, Cenostigma (e.g. https://species.wikimedia.org/wiki/Cenostigma_pyramidale)
- cerrado: Apuleia, Copaifera, Dimorphandra (https://en.wikipedia.org/wiki/Dimorphandra_mollis), Hymenaea, Tachigali (https://archive.org/details/cbarchive_121081_asynopsisfothegenustachigalile2008/page/n9/mode/2up?view=theater)
- chaco: Denisophytum, Copaifera, Cynometra, Hymenaea, Gleditsia (https://www.inaturalist.org/taxa/48497-Gleditsia-amorphoides and https://www.inaturalist.org/observations/99311523 and https://www.inaturalist.org/observations/99370608), Libidibia (https://www.inaturalist.org/observations/99483178)
- Atlantic forest: Paubrasilia (https://en.wikipedia.org/wiki/Paubrasilia), Plathymenia (https://en.wikipedia.org/wiki/Plathymenia and https://www.inaturalist.org/observations/99397857), Schizolobium (https://www.inaturalist.org/observations/97173996 and https://www.inaturalist.org/observations/96300503), Bauhinia forficata
- atacama: Tara spinosa (https://en.wikipedia.org/wiki/Tara_spinosa and https://www.inaturalist.org/observations/49650269)
Ectomycorrizal mutualisms have been recorded in Dicymbe, Eperua and Gleditsia (https://www.academia.edu/27848967/Ectomycorrhizas_in_plant_communities and https://mycorrhizas.info/ecm.html). Fixation of nitrogen in nodules has been recorded in Dimorphandra and Tachigali, the latter being remarkable because this nutritional mode is not usually associated with genera capable of growing into such large trees. The following gives further information on the nutritional modes: https://www.jstor.org/stable/2588772.
To be continued...
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The following liana is pantropical: https://en.wikipedia.org/wiki/Guilandina_bonduc. However, the caesalps of South America are unusual in including a genus consisting entirely of lianas: https://en.wikipedia.org/wiki/Schnella.
The following species extends into South America in the extreme northwest: https://en.wikipedia.org/wiki/Haematoxylum_brasiletto and https://www.inaturalist.org/observations/97361208.
The following are shrubs with restricted distributions in dry climates in South America: https://en.wikipedia.org/wiki/Zuccagnia and https://www.inaturalist.org/observations/97162341 and https://en.wikipedia.org/wiki/Balsamocarpon and https://www.inaturalist.org/observations/96967315.
Parkinsonia is indigenous to both southern Africa (where it is restricted to shrubs) and South America (where it forms small trees): https://en.wikipedia.org/wiki/Parkinsonia and https://www.inaturalist.org/observations/97647670 andhttps://www.inaturalist.org/observations/97090798 and https://www.inaturalist.org/observations/94007753.
Another relevant genus of legumes in South America is Swartzia (https://en.wikipedia.org/wiki/Swartzia), which can perhaps be included among the caesalps.
Africa-South America connection: tribes Cynometreae and Amherstieae, both of which produce resin. Genera involved are Hymenaea, Trachylobium, Copaifera, Guibourtia.
Copaifera (https://en.wikipedia.org/wiki/Copaifera) 25 species in America, 5 species in Africa
Guibourtia (https://en.wikipedia.org/wiki/Guibourtia) 3 species in America, 14 species in Africa
Haematoxylum (https://en.wikipedia.org/wiki/Haematoxylum) 2 species in America, 1 species in Africa
Resin-producing members of Cynometreae are:
Cynometra (pantropical, https://en.wikipedia.org/wiki/Cynometra),
Copaifera (South America and tropical Africa),
Daniellia (tropical Africa, https://en.wikipedia.org/wiki/Daniellia),
Tessmannia (tropical Africa, https://en.wikipedia.org/wiki/Tessmannia),
Guibourtia (South America and tropical Africa),
Colophospermum (tropical Africa, https://en.wikipedia.org/wiki/Mopane),
Trachylobium (tropical Africa and Madagascar, https://en.wikipedia.org/wiki/Hymenaea_verrucosa),
Hymenaea (South America to Caribbean, https://en.wikipedia.org/wiki/Hymenaea),
Peltogyne (South America, https://en.wikipedia.org/wiki/Peltogyne),
Gossweilerodendron (tropical Africa, https://en.wikipedia.org/wiki/Prioria_balsamifera),
Oxystigma (tropical Africa, https://en.wikipedia.org/wiki/Prioria),
Prioria (South America, https://en.wikipedia.org/wiki/Prioria),
Eperua (South America, https://en.wikipedia.org/wiki/Eperua).
Cynometra itself does not produce resin.
Hymenaea occurs in evergreen rainforest, including varzea, plus savanna (including cerrado) and scrub. Hymenaea courbaril (https://en.wikipedia.org/wiki/Hymenaea_courbaril), a widespread species, grows in almost pure stands in deciduous forest in northern Mexico. It is a prominent member of various types of savannas, occurring for example along streams in cerrado in Brazil, in caatinga in Brazil, as scattered trees in llanos in Venezuela, and in thorn forest in Mexico. Hymenaea and its African vicar Trachylobium have indehiscent pods, which can float.
Guibourtia occurs in Africa in evergreen forest, deciduous woodland, and savanna (e.g.in far West Africa). By comparison this genus occurs locally in some areas of caatinga in South America. Guibourtia copallifera (http://tropical.theferns.info/viewtropical.php?id=Guibourtia+copallifera) occurs from Senegambia to southwestern Mali, at the southern edge of the Sahel. How common was it, originally?
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