Didier

Didier's trees are trees 10-15 m high or shrubs 2-6 m high, whose trunks and branches are covered with thorns. They grow in xerophytic forests or in thickets of thorny shrubs, often in a community with leafless milkweeds on calcareous, stony or sandy soils. Occasionally rise into the mountains at an altitude of 900-1200 m above sea level.

Representatives of the family are characterized by the presence of two types of shoots : long with small and rapidly falling leaves and shortened. The latter develop in the axils of the leaves of long shoots and are homologous to the areola in cacti . On young long shoots, thickenings or tubercles, similar to the bases of the leaf in opuntia (cactus), are clearly visible. On shortened shoots spikes and leaves develop singly or in groups, while the leaves are collected in two or in a bundle of up to 10. By the beginning of the dry period (April – May) they fall, and the plant remains without leaves for 5 months. At this time, photosynthesis is carried out by chlorophyll-bearing sections of the stem.

Didier flowers are collected in supra - flowered inflorescences or groups of inflorescences , dioecious, with the exception of flowers of Madagascar decary ( Decaryia madagascariensis ), which has female dioeciousness (gynodiation): on some plants the flowers are bisexual, on the other women.

At the base of each Didieri flower there are two membranous bracts, commonly mistaken for sepals. There are 4 sepals, they are arranged in 2 circles, whitish, yellowish, greenish, brownish, less often carmine-red, and are usually mistaken for petals. No petals. In the male flowers of stamens 8-10 (13), arranged in 2 circles, their filaments are weakly pubescent and slightly fused to the base at the base. They surround a sterile, rudimentary gynoecium. In female flowers, the stamens are turned into staminodes. Gynoecium syncarpous, consists of 3 (4) carpels. The ovary is three-celled, but with one fertile nest, with one direct ovule. The fruit is dry, unbreakable. Seeds with a bent embryo, without an endosperm or with a very scarce endosperm, with a small arylus.

Includes 4 genera:

• Didierea
• Alluaudia
• Alluaudiopsis
• Decarya .

• Biological Encyclopedia.

• Didierp in Cactusopedia (link not available)
• Didier on Academician. RU.

1. ↑ For the conventionality of specifying the class of dicotyledons as a superior taxon for the plant group described in this article, see the APG Systems section of the Dicotyledonous article .