Pterygota Notes

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Synonymy of Pterygota


Pterygota is a genus of malvaceous trees, placed in subfamily Sterculioideae/tribe Sterculieae, with a pan-tropical, rain-forest, distribution. The genus was introduced in 1832 [a]. The number of species is not clear - Kubitzki and Bayer [1] write "probably more than 10 species". The Flora of Madagascar [2] gives a count of 17 species, including two from Borneo, and two from New Guinea. The Flora of China [3] says "about 20 species". There are 4 species in the Neotropics. The African Flowering Plant Database (AFPD) [4] recognises 8 species in Africa, with an additional name (Pterygota kamerunensis K.Schum. & Engl.) of uncertain status, but only 3 of these are at all well known. However the Flora of Tropical East Africa [5] rejects one of these. The flora of Madagascar [2] includes 2 species. The type species, Pterygota alata, is found in south, southeast and east Asia, There is one species from Ceylon. In addition to Pterygota alata there are 5 species from Malesia and Papua. Putting these together produces a count of 21 species, which I present as a tentative enumeration of the species of the genus.

Like the other genera of Sterculioideae species of Pterygota have alternate, petiolate, foliage and possess apetalous (lacking petals), exinvolucellate (lacking an epicalyx) flowers with a fleshy, usually petaloid, gamosepalous (fused) calyx, an absence of staminodes, a monadelphous staminal column, an androgynophore (a stalk separating the calyx from the stamens and styles), and apocarpous (i.e. separated) ovaries and fruits. The key character distinguishing Pterygota from the other genera of the subfamily is the possession of winged seeds. Other traits common in Pterygota are large, broadly ovate to suborbicular, long-petiolate. unlobed, entire-margined, palmately-nerved leaves clustered at the end of branches, pluriovulate ovaries with biserriate axile placentation, and large, many-seeded, ventrally dehiscent, flattened subovoid, stipitate, follicles. The calyx and gynoecium are usually pentamerous. There are exceptions - for example Pterygota horsfieldii has 4- (less commonly 3-)merous calyces and gynoecia, and Pterygota colombiana has narrow, palmatipinnate, leaves.

Neotropical Species

Four species of Pterygota are found in the Americas, where the genus is found in Costa Rica, in northern Colombia and Venezuela, in eastern Brasil, and in Peruvian and Bolivian Amazonia. A single record, not identified to species, is known from Guatemala. Two of these species, P. brasiliensis and P. excelsa, were previously placed in Basiloxylon, which has subsequently been reduced to Pterygota [6].

The American species generally have narrower leaves with less obtuse apices that the Old World species. While the leaves of P. amazonica and P. brasiliensis are 5-nerved at the base, the outermost pair of veins is less prominent that the other 3, and those of P. colombiana are 3-nerved at the base (palmatipinnate).

Pterygota amazonica L.O.Williams
 paujiluro, paujiluro blanco

Pterygota amazonica is found in the Peruvian and Bolivian Amazon. It is a large tree, reaching 130ft in height, and a trunk diameter of 3ft. In mature trees the branches are confined to the top of the tree.

The foliage is clustered at the end of the branches. It is deciduous. The petioles are 2½–4 inches long. The dimensions of the blades are 6×5 to 8×6 inches. They are 5-nerved at the base. The inner pair of veins has 3 to 5 secondary veins on the their outer side only, and the midrib 3 or 4 pairs of secondary veins. The inflorescences are axillary. They are relatively short and few-flowered. The follicle is large (4-5 inches in length, 4 inches in breadth, and 2½ inches in depth), woody and long stipitate, with a fine tomentum. It contains about 20 seeds. Including the wing the seeds are 2½–3 inches long, and 1 inch or a little less wide. [6].

Pterygota brasiliensis Allemão & M.Allemão
 Farinha-seca, Folheiro, Maperoá, pau-rei

Pterygota brasiliensis is native to the Atlantic coastal forest of Brasil. Its leaves are palmately 5-nerved.

Synonyms of Pterygota brasiliensis include Basiloxylon brasiliensis (Allemo) K.Schum. in Engl. & Prantl and Sterculia rex Mart. ex K.Schum..

Pterygota colombiana Cuatrec.

Pterygota columbiana is native to eastern Columbia (Santa Marta) and western Venezuela. It differs from the other American species in possessing narrower, palmatipinnate (3-nerved at the base) leaves.

Pterygota excelsa (Standl. & L.O.Williams) Kosterm.

Pterygota excelsa is said to be endemic to wet lowland forests in Costa Rica. However it is also reported from the Uraba and Rio Magdalena regions of Colombia. It is a tall buttressed tree.

The foliage is deciduous (in the dry season), alternate and long-petiolate. The leaf-blades are large, unlobed, broadly ovate, palmately 5–7-nerved, obtuse or broadly cordate at the base, acuminate at the apex. The flowers are borne in February and March. The sepals are green, lightly striped with maroon inside. The anthers are bright yellow. The follicles of the fruit are large (6 inches in length, 3½ inches in breadth, and 2 inches in depth), woody, and dehiscent. They contain many large (3 inches long) winged seeds.

Basiloxylon excelsum Standl. & L.O.Williams is a synonym of Pterygota excelsa.


African Species

In addition to the species listed here, the Malagasy Pterygota perrieri also occurs in Mozambique, Tanzania and the Comoros [5].

Pterygota schumanniana is poorly known, and the type specimen is presumed to have been destroyed during the Second World War. However, the Flora of Tropical East Africa identifies this as a synonym of Pterygota mildbraedii.

Pterygota adolfi-friederici Engl. & K.Krause

Pterygota adolfi-friederici has been collected on a number of occasions in the south east of Cameroun. Although recognised by AFPD the expedition report describing some of these collections assigns them to Cola gigantea, which casts doubt on its validity.

There are no known synonyms of Pterygota adolfi-friederici.

Pterygota augouardii Pellegr.

Pterygota augouardii was long known only from the type, collected in Gabon in 1915 [4], but has recently been recorded from Combretum-Terminalia woodland in northern Namibia, and from the Central African Republic.

There are no known synonyms of Pterygota augouardii.

Pterygota bequaertii De Wild.

Pterygota bequaertii is recorded widely within lowland rainforest and gallery forests in western and central Africa, from southern Ivory Coast, southern Nigeria, Gabon, both Congos [4], and Ghana and Cameroon [7].

Its timber is commercially exploited, under the name koto.

Synonyms of Pterygota bequaertii include Pterygota aubrevillei Pellegr. and Sterculia bayakensis Pellegr..

Pterygota kamerunensis K.Schum. & Engl.

Pterygota kamerunensis is of uncertain status [4].

Pterygota macrocarpa K.Schum.