The families of flowering plants
Habit and leaf form. Shrubs. Leaves small; alternate; closely crowded towards the branch tips, spiral; imbricate; petiolate; simple. Lamina entire; obovate (spathulate); seemingly parallel-veined (see illustration in the original description); seemingly cross-venulate; attenuate at the base. Leaves exstipulate. Lamina margins entire; revolute (and the lamina externally pouched at the apex).
Leaf anatomy. Stomata present; mainly confined to one surface (borne on (confined to?) the inner surface of the pouch); anisocytic. Adaxial hypodermis absent. The mesophyll without crystals.
Axial (stem, wood) anatomy. Internal phloem present. Secondary thickening developing from a conventional cambial ring.
The vessel end-walls scalariform. The parenchyma lacking.
Reproductive type, pollination. Plants hermaphrodite. Floral nectaries represented by glands at the bases of the sepals?.
Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; fairly showy; regular; (4–)5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; (8–)10; 2 whorled; isomerous. Calyx (4–)5; 1 whorled; gamosepalous (basally); regular. Corolla (4–)5; 1 whorled; gamopetalous; lobes imbricate; with a well developed tube; regular.
Androecium (4–)5. Androecial members adnate; all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; inserted near the base of the corolla tube, or midway down the corolla tube (halfway or more down); isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments quite long, but the anthers enclosed by the corolla). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; latrorse to introrse; tetrasporangiate; appendaged. The anther appendages apical (by extension of the connective into an evident point). Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 2 locular (but the partitions imperfect towards the apex); sessile. Gynoecium stylate. Styles 1; more or less attenuate from the ovary; apical; much longer than the ovary (but included). Stigmas 1–2 (shortly bilobed). Placentation axile (distally intruded-parietal). Ovules 30–70 per locule (many); anatropous; unitegmic (the single integument massive); tenuinucellate.
Physiology, phytochemistry. Alkaloids seemingly absent. Iridoids apparently detected.
Special distinguishing feature. Lamina exhibiting revolute margins continuous with a characteristic, abaxially pouched tip.
Geography, cytology. Neotropical. Guayana Highland.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Gentianiflorae (?); Gentianales (?). Cronquists Subclass Asteridae; Gentianales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; lamiid; Order Gentianales (as a synonym of Gentianaceae).
Species 1. Genera 1; only genus, Saccifolium.
General remarks. See Maguire and Pires 1978. Ostensibly differing from Gentianaceae (q.v.) in the scalariform vessel end-walls, as well as the peculiar leaf form.
Illustrations. • Saccifolium bandeiri (Mem. New York Bot. Gard., 1978).
The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. 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: 16th May 2016. delta-intkey.com’.