Family Dracaenaceae

Dracaenaceae R.A. Salisbury

~ Formerly Agavaceae, APG Asparagaceae-Nolinoideae

Including Sansevieriaceae Nak.

Habit and leaf form. Shrubs, or herbs, or ‘arborescent’. ‘Normal’ plants. Plants succulent, or non-succulent. With a basal aggregation of leaves, or with terminal aggregations of leaves (often with apical rosettes), or with neither basal nor terminal aggregations of leaves. Self supporting, or climbing. Often pachycaul. Mesophytic, or xerophytic. Leaves small to very large; alternate; spiral; ‘herbaceous’, or leathery, or fleshy; petiolate to sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Lamina entire; linear, or lanceolate, or ovate; palmately veined, or parallel-veined; without cross-venules.

Leaf anatomy. Stomata present; anomocytic.

The mesophyll containing mucilage cells (with raphides); containing calcium oxalate crystals. The mesophyll crystals raphides and solitary-prismatic. Vessels present; end-walls scalariform.

Stem anatomy. Secondary thickening anomalous; from a single cambial ring. Xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls simple (?).

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in umbels, or in panicles. The ultimate inflorescence unit racemose. Inflorescences pedunculate; axillary; racemes or panicles, elongated or umbellate; espatheate. Flowers minute to large; regular; 3 merous; cyclic; pentacyclic. Perigone tube present.

Perianth of ‘tepals’; 6; joined; 2 whorled; isomerous; petaloid; similar in the two whorls.

Androecium 6. Androecial members adnate (at the bases of the tepal lobes); all equal; free of one another; 1 whorled, or 2 whorled (?). Androecium exclusively of fertile stamens. Stamens 6; diplostemonous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate. The endothecial thickenings spiral. Microsporogenesis successive. Pollen grains aperturate; 1 aperturate; ulcerate; 2-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1; trilobate or capitate; wet type. Placentation axile. Ovules 1 per locule; anatropous; pseudocrassinucellate. Embryo-sac development Polygonum-type. Endosperm formation probably nuclear.

Fruit fleshy (usually), or non-fleshy; indehiscent; a berry (usually, typically red or orange), or a capsule, or capsular-indehiscent (sometimes woody). Seeds endospermic. Endosperm oily. Cotyledons 1. Embryo straight. Testa without phytomelan.

Seedling. Hypocotyl internode present (short). Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls present. Primary root persistent (Dracaena), or ephemeral (Sanseviera).

Physiology, biochemistry. Not cyanogenic. Alkaloids absent (?). Proanthocyanidins absent. Flavonols present (Dracaena), or absent (Sanseviera); kaempferol. Ellagic acid absent. Saponins/sapogenins present. C3 and CAM. CAM recorded directly in Sansevieria. Anatomy non-C4 type (Dracaena).

Geography, cytology. Holarctic, Paleotropical, Neotropical, Cape, and Australian. Sub-tropical and tropical. Subtropical/tropical old world, rainforest and savanna.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Asparagales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Asparagales (as a synonym of Asparagaceae).

Species about 160. Genera 2; Dracaena, Sanseviera.

Illustrations.
• Dracaena: habit and LS flower (Thonner).
• Dracaena brasiliensis: habit (Chittenden).