Portulacaceae

Primary tabs

Portulacaceae

Description

Annual to perennial, erect or creeping, mostly branched herbs or shrubs, occasionally woody at the base, often with a tuberous or swollen main root, occasionally rooting at the nodes. Leaves spirally arranged to opposite, subsessile, occasionally with axillary hairs or scales (in Mal. only in Portulaca), nervation pinnate or reticulate. Flowers bisexual, actinomorphous (occasionally cleistoga-mous), in axillary and/or terminal thyrsi, dichasia, in terminal capitules or solitary (terminal or axillary). Sepals 2 (4-8 in extra-Mal. Lewisia and Grahamia), boat-shaped, deltoid to obovate at base shortly connate and confluent with petals and stamens. Petals (3-)4-6(-8), mostly obovate and unequal, shortly connate. Stamens (1-)3-∞, in 1-∞ ± distinct whorls; Ovary superior or half-inferior, originally 2-20-celled, soon becoming 1-celled; Capsule 3-7-valved or with a caducous operculum, occasionally surrounded by the persistent calyx. Ovules 4-∞ on a central, dendroid placenta, campylotropous. Seeds 1-∞, smooth or ornamented, kidney-shaped to ± globular, laterally compressed, mostly with a caruncle.

Distribution

Asia-Tropical: Cosmopolitan: present
About 15 genera with possibly 200 spp. Cosmopolitan, with some tropical species occurring as adventives in temperate regions. In Malesia 4 genera with 11 spp.

Morphology

VON POELLNITZ (, and other papers) called the sepals "Involucralblätter", suggesting their homology with the involucral leaves surrounding the capituli, the latter being called by him "falsche Involucralblätter". Also LEGRAND (in Com. Bot. Mus. Hist. Nat. Montevideo 31, 1, 1953, 1, and other papers) called the calyx lobes "pseudosepalos".
Taking into account, that the calyx normally is considered as (metamorphosed) leaves and that in Portulacaceae the phyllotaxal position of the sepals is so distinctly set off against the bracts, it seems to me that there is no morphological argument to accept the flower as being monochlamydeous.

Anatomy

See also my precursory paper () on the axillary hairs; .

Uses

See . See also under the species.

Phytochemo

Red betacyanins (replacing anthocyanins) and yellow betaxanthins form an outstanding chemical character of the family. Such nitrogen-containing pigments (chromoalkaloids) were demonstrated to be present in members of the genera Anacampseros, Calandrinia, Claytonia, Montia, Portulaca, Spraguea, and Talinum. Saponins seem to occur frequently in the family; their chemistry, however, is not yet known. The seeds store starch in the perisperm and fatty oil in embryos; at the same time they contain appreciable amounts of protein. The chemical features known at present from this family confirm its intimate relationships with other members of the centrospermous alliance. A summary of phytochemical literature is to be found in . — R. HEGNAUER.