The families of flowering plants
~ Apocynaceae, Loganiaceae
Habit and leaf form. Trees and shrubs; non-laticiferous and without coloured juice. Plants non-succulent. Leaves evergreen; small; (sub) whorled, or opposite; leathery; shortly petiolate; not connate; simple. Lamina entire; oblong to ovate (sometimes emarginate). Leaves exstipulate. Lamina margins entire; slightly revolute.
Leaf anatomy. Stomata present; anomocytic. Hairs present; eglandular and glandular (eglandular-unicellular and glandular-bicellular). Unicellular hairs unbranched. Complex hairs present, or absent; if present, capitate.
Lamina dorsiventral. Cystoliths present (adjoining the bases of the CaCO2-filled, unicellular hairs).
Reproductive type, pollination. Plants hermaphrodite; homostylous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences (in groups of 17, pedicellate). The ultimate inflorescence unit racemose. Inflorescences axillary; axillary, 17 flowered, racemose but the peduncle and axis very short. Flowers regular to somewhat irregular; slightly zygomorphic; 5–6 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; 10, or 12; 2 whorled; isomerous. Calyx 5, or 6; 1 whorled; basally gamosepalous (small); blunt-lobed to toothed (the lobes lanceolate). Calyx lobes markedly longer than the tube. Calyx unequal but not bilabiate, or regular; persistent; non-accrescent; imbricate, or open in bud. Corolla 5, or 6; 1 whorled; gamopetalous (glabrous within); imbricate (the lobes broad, rounded); campanulate, or funnel-shaped; slightly unequal but not bilabiate, or regular; purple, or blue (or violet).
Androecium 5, or 6. Androecial members adnate (inserted in the corolla tube); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5, or 6; isomerous with the perianth; oppositisepalous; alternating with the corolla members; quite long filantherous. Anthers dorsifixed (ovate, basally cordate); dehiscing via longitudinal slits; more or less latrorse, or introrse. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious to synstylovarious (the style bifid above, its branches each apically two-lobed); superior. Ovary 1 locular; shortly stipitate. Gynoecium stylate. Styles 1–2 (deciduous); without an indusium; partially joined (i.e. the style bifid above); apical. Stigmas 4 (these small, clavate). Placentation basal to parietal, or parietal to apical (or both). Ovules in the single cavity 2, or 4; ascending, or pendulous and ascending (there being two parietal placentas, these with one or two basal-erect ovules each, or having two basal-erect ovules on one and two subapical-pendulous ovules on the other).
Fruit non-fleshy; dehiscent; a capsule (elongate-fusiform, ribbed). Capsules (two-) valvular (from the apex). Fruit 1 seeded (usually), or 1–4 seeded. Seeds sparsely endospermic (the endosperm fleshy); long-linear, subterete; apically conspicuously hairy (with a dense tuft). Embryo straight (linear).
Physiology, biochemistry. Iridoids not detected. Verbascosides detected. Cornoside detected.
Geography, cytology. Neotropical. Sub-tropical to tropical. Mexico, Central America.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Lamiiflorae; Scrophulariales (?). Cronquists Subclass Asteridae; Gentianales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Lamiales.
Species 3. Genera 1; only genus, Plocosperma (including Lithophytum).
General remarks. See Leeuwenberg 1980, under Loganiaceae.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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).
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 December 2012. http://delta-intkey.com’.