In the wild (the dry spiny forests of western and southwestern Madagascar), one often sees these plants growing on top of shrubs and small trees.
The climbing or creeping branches are up to 5 m long; they bear few tendrils, which are branched at their tips and grey-green leaves, which are 3.5-5.5 cm long and 2.5-5 cm wide.
The inconspicuous flowers are greenish-yellow.
Over a period of hundreds of years, a great part of the original forest vegetation of Madagascar’s Central Plateau has been destroyed by annual burning.
The resulting savannah-like grasslands are very poor in species. A few succulents can survive the fires, either because they have very thick and fleshy leaves, e.g. the subject of this post, or because they hide underground (such as geophytic Euphorbias, see Euphorbia primulifolia).
A. macroclada is an impressive plant with its leaves up to a meter long and 17-22 cm wide at the base. In winter, the stemless rosettes are adorned with (usually single) inflorescences which in old specimens may be up to 2.5m tall. The many flowers are 2-2.5 cm long and 2 cm wide at the mouth.
It is probably the most widely distributed of the Madagascan Aloes, from 200 km north of Antananarivo to Fort Dauphin in the far south, usually at altitudes between 1200 and 1500 m.
There is only one place in the world where this species is known to occur: Tanjona Vohimena, the southernmost tip of Madagascar*.
On this stark, wind-swept limestone terrace about 100 m above sea level, the species occupies an area of less than a km².
Old plants possess a large turnip-shaped root to 30 cm long and to 10 cm wide, topped by a densely branched crown to 30 cm in diameter. In habitat the branches creep along the ground as a result of the constant wind; in cultivation they are more or less erect.
The leaves form rosettes at the tips of the branches, they are to 25 x 8 mm in size and green to red-brown.
* The old name for this is Cap Sainte Marie, which explains the specific epithet.
Plant in cultivation; scanned slide
In the dormant state, without leaves and flowers, this species is difficult to distinguish from P. densiflorum and P. rosulatum. They share the same habit: low, multi-branched shrubs up to 1.5 m in diameter and up to 1 m tall.
P. horombense is named after the Horombé plateau in the southern highlands of Madagascar, where it often occurs in great numbers on granite rocks.
The inflorescence has an erect peduncle of no less than 60 cm tall, with broadly cup-shaped flowers 1.7-2.3 cm in diameter.
According to Werner Rauh in his great book on the succulents of Madagascar, this is:
“the most beautiful Pachypodium species in cultivation”.
Uncarina is a genus of 12 species occurring in northern, western and southwestern Madagascar.
U. stellulilifera is common between limestone rocks in the Tulear region, between Morondava in the north and Lake Tsimanampetsotse in the south.
It is a small tree up to 3.5 m tall, with a thickened base and leaves 4-12 cm long and 3-10 cm wide. The beautiful flowers are 5-6 cm long.
The fruits are most peculiar with their very long barbed spines, which attach them to passing animals as an aid in dispersal. We were told that the local people use the fruits to catch mice.