The families of flowering plants
~ Formerly Agavaceae, APG Asparagaceae-Nolinoideae.
Including Sansevieriaceae Nak.
Habit and leaf form. Shrubs, or herbs, or arborescent. Plants succulent, or non-succulent. With a basal aggregation of leaves, or with terminal aggregations of leaves (often with apical rosettes), or without conspicuous 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 crystals. The crystals raphides and solitary-prismatic. Foliar vessels present; with scalariform end-walls.
Axial (stem, wood) anatomy. Secondary thickening anomalous. The anomalous secondary thickening from a single cambial ring. The axial xylem without vessels.
Root anatomy. Root xylem with vessels; vessel end-walls simple (?).
Reproductive type, pollination. 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 units racemose. Inflorescences pedunculate; axillary; racemes or panicles, elongated or umbellate. 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. Tepal apex trichomes (TAT) present (Dracaena, Sanseviera).
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, phytochemistry. C3 and CAM. CAM recorded directly in Sansevieria. Anatomy non-C4 type (Dracaena). Not cyanogenic. Alkaloids absent (?). Saponins/sapogenins present. Proanthocyanidins absent. Flavonols present (Dracaena), or absent (Sanseviera); kaempferol. Ellagic acid absent.
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.
General remarks. In addition to features consequent on their not being switch plants, these plants differ from Asparagaceae sensu stricto (q.v.) in exhibiting anomalous secondary thickening of stems and xylem without vessels, as well as in inflorescence, pollen and ovule characters.
Illustrations. • Dracaena: habit and LS flower (Thonner). • Dracaena brasiliensis: habit (Chittenden).
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 October 2016. delta-intkey.com’.