Pachypodium brevicaule

Description

Pachypodium brevicaule is a species of plant that belongs to the family Apocynaceae. This plant is native to Madagascar, from the south of Antananarivo to the Itremo Mountains. A flattened, tuberous, cactus-like plant with a very low trunk and a very wide, exaggerated diameter without substantive branching whatsoever with exception to several extremely short flattened "branch"-like nodes or rosettes of leaves. Pachypodium brevicaule Baker grows in open, deciduous Western forest of Madagascar in full sun on sandstone, rarely on granite, in crevices between outcrops of quartzite. With a pH. Level varying from 3.5 to 4.5, it is strictly adapted to growing in acid substrates. (That strictness to acidity seemingly has implications to its cultivation.) It is found in the evergreen Sclerophyllous (Uapaca) woodland or savanna zones dominated by scattered woody plants. It grows at altitudes of 1250–1900 m (sometimes 2000 m). Associated plant species, site indicators, include Pachypodium densiflorum, P. eburneum (Apocynaceae), Aloe compressa, A. capitata, (Asphodelaceae), Euphorbia quartzicola (Euphorbiaceae), (Orchidaceae), (Graminaea), (Bryophyta), and Lichenes. It occurs in a region that receives an annual rainfall of 1354 mm with a number of 5 dry months. Average monthly temperatures varies from 9 °C to 17 °C. The yearly average temperature is higher; however, at 13 °C to 18.4 °C. Pachypodium brevicaule is unique to the genus in habit. It is considered a dwarf plant. It takes on a broad flattenened tuberous, cactus-like habit that has a very short trunk measuring 2 to 8 cm high and an exaggerated diameter that can reach 10 to 40 cm. When in flower the plant gains stature by reaching a height of 25 cm. Pachypodium brevicaule Baker barely, if all, "branches." Rather it seems to form protruding nodes or rosettes of leaves that ranch from 1 to 4 cm in length and 2 to 4 cm in width. In the "Botanical Key for the Genus Pachypodium," the character "without branches or branchlets" is a distinguishing morphological character to the species Pachypodium brevicaule's definition. The bark is colored pale grey and is sometimes shiny. It has a smooth texture. The bark is about 2 to 4 mm thick, with the wood being greenish. The "branches" or, better said, nodes of rosettes of leaves, when fresh, have paired, rather soft, curved spines at their apices, measuring 2 to 9 mm long by 1 to 1.5 mm at the base.