The families of flowering plants.
Habit and leaf form. Herbs;non-laticiferous and without coloured juice. Densely caespitose, perennial. Leaves small; alternate; leathery; densely imbricate; simple. Lamina entire. Leaves exstipulate. Lamina margins entire.
Stem anatomy. Secondary thickening absent, or developing from a conventional cambial ring (?). Sieve-tube plastids P-type; type III (a).
Reproductive type, pollination. Plantspolygamomonoecious (?).
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; bracteolate (with 2–3 bracteoles), or ebracteolate; regular. Free hypanthium absent.
Perianthwith 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.
Androecium3–5(–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.
Geography, cytology. Antarctic. Frigid zone (Antarctic), or temperate. New Zealand, Kerguelen Is.
Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG 3 core angiosperms; core eudicot; Superorder Caryophyllanae; Order Caryophyllales (as a synonym of Portulacaceae).
Species 2. Genera 2; Hectorella, Lyallia.
General remarks. See Philipson and Skipworth (1961).