Family Xeronemataceae

Xeronemataceae M.W. Chase, Rudall & M.F. Fay

~ Asphodelaceae, Phormiaceae, Hemerocallidaceae

Habit and leaf form. Shrublike herbs. Perennial; with a basal aggregation of leaves (borne in fans); about 0.5–1.3 m high; rhizomatous (and stemless). Xerophytic. Leaves large to very large; alternate; distichous; flat; leathery and fleshy (the bases fleshy); sessile; strongly sheathing (with a distinct sinus between sheath and blade). Leaf sheaths with free margins. Leaves edgewise to the stem (broadly ensiform, equitant and isobilaterally flattened); simple. Lamina entire; lanceolate; parallel-veined; without cross-venules. Leaves with a persistent basal meristem, and basipetal development.

Leaf anatomy. Stomata present; on both surfaces.

Lamina isobilateral. The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides (these abundant, but no styloids).

Root anatomy. Root xylem with vessels.

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (via highly branched septal nectaries, which extend from the base of the ovary to openings around the base of the style). Pollination entomophilous, or ornithophilous (?).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes (congested). The ultimate inflorescence unit racemose. Inflorescences scapiflorous (the scape with sheathing bracts subtending the horizontal racemes well above the leaves); terminal; “dense, brushlike spikes”. Flowers bracteate; ebracteolate; medium-sized; regular; 3 merous; cyclic; pentacyclic. Perigone tube absent. Hypogynous disk absent.

Perianth of ‘tepals’ (these about 2 cm long); 6; free; 2 whorled (3+3); isomerous; petaloid; similar in the two whorls; red (along with all the inflorescence components).

Androecium 6. Androecial members free of the perianth; more or less all equal; free of one another; 2 whorled (3+3). Stamens 6; diplostemonous; alterniperianthial. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. Microsporogenesis probably simultaneous. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; mostly 1 aperturate; mainly mono- sulcate (with a few trichotomosulcate grains); scabrous, or muricate.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles attenuate from the ovary; apical; much longer than the ovary. Stigmas 1. Placentation axile. Ovules 3–10 per locule (“several”); non-arillate; hemianatropous, or anatropous (?); bitegmic; crassinucellate. Embryogeny caryophyllad.

Fruit non-fleshy; dehiscent; a capsule (purplish). Capsules loculicidal. Dispersal unit the seed. Fruit many. Seeds endospermic; small to medium sized (about 5 mm long); wingless. Embryo well differentiated. Cotyledons 1. Testa with spines, or with tubercles; encrusted with phytomelan; black.

Seedling. Coleoptile absent.

Physiology, biochemistry. C3, or CAM (?).

Geography, cytology. Paleotropical and Antarctic. Frigid zone and tropical. Restricted to New Zealand (X. callistemon) and New Caledonia (X. moorei). 2n=36 (X. moorei) and 72 (X. callistemon).

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Asparagales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Asparagales.

Species 2. Genera 1; Xeronema.

Moore (1957); Clifford et al. in Kubitzki (1998); Chase et al (2000).