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The families of flowering plants

L. Watson and M. J. Dallwitz

Dicrastylidaceae J. Drumm. ex Harv.

Alternatively Chloanthaceae Hutch.; ~ Verbenaceae or Labiatae.

Habit and leaf form. Shrubs (often tomentose). ‘Normal’ plants to switch-plants (Spartothamnella), or ‘normal’ plants. Leaves well developed (though sparse and contributing to the broomlike habit of Spartothamnella). Mesophytic, or xerophytic. Leaves evergreen; opposite, or whorled (rarely alternate); ‘herbaceous’, or leathery; subsessile to sessile; aromatic (?), or without marked odour (Physopsideae); simple. Lamina entire; linear, or lanceolate, or oblong, or ovate; pinnately veined; cross-venulate. Leaves exstipulate; leaf development not ‘graminaceous’.

Leaf anatomy. Hairs present. Complex hairs present; peltate, or stellate.

Axial (stem, wood) anatomy. Internal phloem absent. Secondary thickening anomalous. The anomalous secondary thickening via concentric cambia (all the genera).

The axial xylem with fibre tracheids; including septate fibres (at least sometimes), or without septate fibres (?). ‘Included’ phloem present.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in panicles, or in heads, or in corymbs, or in spikes. Inflorescences terminal, or axillary; spicate, capitate or compound. Flowers bracteate; regular, or somewhat irregular, or very irregular; when irregular, zygomorphic. The floral irregularity (when manifest) involving the perianth, or involving the perianth and involving the androecium. Flowers neither papilionaceous nor pseudo-papilionaceous; 4–8 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 8–16; 2 whorled; isomerous. Calyx 4–8; 1 whorled; gamosepalous; regular; persistent; accrescent (rarely, enlarging in the fruit), or non-accrescent. Corolla 4–8 (or almost truncate); 1 whorled; gamopetalous; imbricate; more or less unequal but not bilabiate to bilabiate (usually), or regular.

Androecium 4–8, or 3–7. Androecial members adnate (epipetalous); free of one another; 1 whorled. Androecium exclusively of fertile stamens (mostly), or including staminodes (Hemiphora). Staminodes in Hemiphora 2; in the same series as the fertile stamens; representing in Hemiphora, the posterior-lateral pair. Fertile stamens representing the posterior median member, the posterior-lateral pair, and the anterior-lateral pair, or the posterior-lateral pair and the anterior-lateral pair, or the anterior-lateral pair. Stamens 4–8, or 3–7, or 2 (Hemiphora); inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; reduced in number relative to the adjacent perianth, or isomerous with the perianth (usually as many as the corolla lobes or one fewer); oppositisepalous; alternating with the corolla members. Anthers dorsifixed; dehiscing via longitudinal slits (mostly), or dehiscing by longitudinal valves (Hemiphora); appendaged (in Pityrodia), or unappendaged. The anther appendages of Pityrodia basal. Pollen grains aperturate; 3 aperturate; colpate.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled, or 4 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 2 locular (morphologically), or 4 locular (sometimes, ostensibly, by intrusion from the walls of ‘false septa’). Locules secondarily divided by ‘false septa’, or without ‘false septa’. Gynoecium median. Styles 1; apical. Stigmas 1 (e.g. Newcastelia, Physopsis), or 2 (mostly). Placentation axile. Ovules 2 per locule, or 1 per locule (when ‘false cells’ are interpreted as locules); non-arillate; hemianatropous; unitegmic; tenuinucellate. Polar nuclei fusing only after one has been fertilized, or fusing simultaneously with the male gamete (?). Antipodal cells formed; not proliferating; ephemeral. Synergids hooked.

Fruit non-fleshy (usually), or fleshy (rarely); indehiscent; a drupe, or a nut. The drupes with separable pyrenes (these two, representing the ‘true’ locules), or with one stone. Fruit 1–2 seeded. Seeds endospermic (mostly), or non-endospermic (Spartothamnella). Embryo straight.

Physiology, phytochemistry. Not cyanogenic. Iridoids detected. Proanthocyanidins absent.

Geography, cytology. Temperate to tropical. Tropical East Africa, Madagascar, Mascarenes, Australasia, Pacific.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Lamiiflorae; Lamiales. Cronquist’s Subclass Asteridae; Lamiales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Lamiales (as a synonym of Labiatae).

Species 90. Genera 11; Chloanthes, Cyanostegia, Denisonia, Dicrastylis, Hemiphora, Lachnostachys, Mallophora, Newcastelia, Physopsis, Pityrodia, Spartothamnella.

General remarks. These genera are part of the Labiatae/Verbenaceae imbroglio: see remarks under Labiatae. Comparing the descriptions compiled here shows this family differing from Labiatae sensu stricto (q.v.) in the anomalous secondary thickening of stems, details of xylem anatomy, ovary placentation and fruit morphology. The attempted description of Verbenaceae (q.v.) differs from this one only in stem anatomy and xylem details.

Illustrations. • Dicrastylis doranii (as carnegiei): Hook. Ic. Pl. 26 (1899). • Chloanthes, Lachnocephalus and Pityrodia: Nat. Pflanzenfam. IV (1897). • Foliar hairs of Pityrodia bartlingii, with those of assorted Labiatae and Verbenaceae (El-Gazzar). • Foliar hairs of Pityrodia salvifolia, with Avicennia nitida (Avicenniaceae) and Clerodendron and Petraea (Verbenaceae) (Solereder, 1908).

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.’.