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~ Portulacaceae.
Habit and leaf form. Herbs. Densely caespitose, perennial. Leaves small; alternate; leathery; densely imbricate; simple. Lamina entire. Leaves exstipulate. Lamina margins entire.
Axial (stem, wood) anatomy. Secondary thickening absent, or developing from a conventional cambial ring (?).
Reproductive type, pollination. Unisexual flowers present. Plants polygamomonoecious (?).
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; bracteolate (with 2–3 bracteoles), or ebracteolate; regular. Free hypanthium absent.
Perianth with distinct calyx and corolla, or sepaline (since postulated relationship with Portulacaceae implies that the ‘sepals’ represent modified bracteoles, the ‘corolla’ a petaloid calyx); 6, or 7; 1 whorled, or 2 whorled (as interpreted here); anisomerous. Calyx 2 (anterior/posterior); 1 whorled; polysepalous; persistent; median. Corolla 4–5; polypetalous, or gamopetalous (then shortly connate). Corolla lobes markedly longer than the tube.
Androecium 3–5(–6). Androecial members free of the perianth, or adnate (to the corolla tube, when this present); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 3–5(–6); reduced in number relative to the adjacent perianth, or isomerous with the perianth; oppositisepalous (alternating with the petals, by contrast with Portulacaceae). Anthers versatile. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 1 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1–2. Placentation free central (the ovules borne near the base). Ovules in the single cavity 4–7.
Fruit non-fleshy; dehiscent; a capsule; 1–5 seeded. Seeds endospermic (unless the ‘endosperm’ is perisperm, cf. Portulacaceae). Perisperm present, or absent (?). Embryo well differentiated. Embryo curved.
Physiology, phytochemistry. Betalains present. Sieve-tube plastids P-type; type III (a).
Geography, cytology. Antarctic. Frigid zone (Antarctic), temperate. New Zealand, Kerguelen Is.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales (as a synonym of Portulacaceae).
Species 2. Genera 2; Hectorella, Lyallia.
General remarks. See Philipson and Skipworth (1961). The differences from Portulacaceae in sexuality and floral morphology seem clear in these descriptions, but as usual in such situations, the present compilations may under-estimate variation in the larger family.
Illustrations. • Hectorella caespitosa: Hook. Ic. Pl. 11 (1867–71). • Lyallia kerguelensis: Hooker, Fl. Antarctica (1844).
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th May 2024. delta-intkey.com’.
