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Family: Portulacaceae

Kingdom: Plantae Rank: Family Parent: Caryophyllales Status: Valid

Common Names:

  • PURSLANE FAMILY - English, United States of America

Morphological Description

Family Recognition in the Field: Herbs with stems or leaves fleshy and often mucilaginous; leaves simple, entire; flowers with 2 sepals and 4-5(-6) petals; fruit a capsule.

Diagnosis: Ours annual or perennial herbs; leaves fleshy, flattened to terete, alternate or opposite, simple, entire; flowers solitary or in corymbose panicles or racemes; sepals 2, separate, sometimes falling early; petals usually 4-5(-6), separate; stamens 5-many; pistil 1; ovary superior or half inferior; fruit a capsule, 3-valved or circumscissile.

Other

Notes: A small (380 species in 32 genera), cosmopolitan, especially w North American family of usually succulent herbs and shrubs with mucilaginous tissues and betalain pigments; it includes various ornamentals. A number of species have specialized Kranz ("wreath") anatomy and the associated C4 photosynthetic pathway, adaptations for hot dry conditions (the C4 pathway allows for a more efficient capture of CO2 thereby reducing the degree to which the stomata have to be open and thus the amount of water lost through transpiration). The family is possibly polyphyletic or paraphyletic and may be ancestral to Cactaceae (Rodman 1990; Downie & Palmer 1994); a recent study by Hershkovitz and Zimmer (1997) indicated on the basis of molecular data that the Cactaceae is derived from within the Portulacaceae and that the molecular divergence "... between pereskioid cacti and the genus Talinum (Portulacaceae) is less than that between many Portulacaceae genera." The Portulacaceae also seems related to the Basellaceae (Rodman et al. 1984; Carolin 1993). Plant anatomists/morphologists consider the perianth to be of a single series, with the petal-like structures actually sepals and the sepal-like structures actually bracts (Tyrl et al. 1994); for convenience we are following most taxonomists and using the terms sepals and petals. (subclass Caryophyllidae).