Family Sphenocleaceae

Sphenocleaceae (Lindl.) Mart. ex DC.

~ Campanulaceae

Including Pongatieae (Pongatiaceae) Endl.

Habit and leaf form. Herbs; non-laticiferous and without coloured juice. Plants (stems) more or less succulent. Annual. Helophytic. Leaves alternate; spiral; non-sheathing; simple. Lamina entire; pinnately veined. Leaves exstipulate.

General anatomy. Plants with laticifers (perhaps, in the phloem), or without laticifers (?).

Leaf anatomy. Stomata tetracytic.

Lamina dorsiventral. The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses.

Stem anatomy. Stems with hollow internodes. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Vessel end-walls simple.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spikes. The ultimate inflorescence unit racemose. Inflorescences terminal; dense spikes. Flowers bracteate; bracteolate (two bracteoles); small; regular; 5 merous; cyclic; tetracyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; gamosepalous; regular; persistent; imbricate. Corolla 5; 1 whorled; gamopetalous; imbricate; campanulate, or urceolate; regular.

Androecium 5. Androecial members adnate (to the corolla); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments short). Anthers dehiscing via longitudinal slits; introrse. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral (usually), or isobilateral (rarely). Anther wall initially with one middle layer (?). Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate (to colporoidate); 3-celled.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; partly inferior to inferior. Ovary 2 locular. Styles 1; apical. Stigmas 1; capitate. Placentation axile (the placentas stipitate). Ovules 10–50 per locule (‘many’); non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Endosperm formation cellular. Embryogeny onagrad.

Fruit non-fleshy; dehiscent; a capsule. Capsules circumscissile. Fruit 15–100 seeded (‘many’). Seeds more or less non-endospermic; minute. Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found.

Peculiar feature. Lamina tip not abaxially pouched.

Geography, cytology. Tropical. Pantropical. N = 12.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Asteriflorae; Campanulales. Cronquist’s Subclass Asteridae; Campanulales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Solanales.

Species 2. Genera 1; only genus, Sphenoclea.