The Families of Flowering Plants
The Families of Flowering Plants | |
~ Gentianaceae
Habit and leaf form. Shrubs. Leaves small; alternate; spiral (closely crowded towards the branch tips); 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 calcium oxalate crystals.
Stem anatomy. Internal phloem present. Secondary thickening developing from a conventional cambial ring. Xylem with vessels. Vessel end-walls scalariform. Wood 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.
Fruit unknown.
Physiology, biochemistry. Alkaloids seemingly absent. Iridoids ‘apparently’ detected.
Peculiar feature. Lamina exhibiting revolute margins continuous with a characteristic, abaxially pouched tip.
Geography, cytology. Neotropical. Guayana Highland.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae (?); Gentianales (?). Cronquist’s Subclass Asteridae; Gentianales. APG (1998) Eudicot; core Eudicot; Asterid; Euasterid I; Gentianales (as a synonym of Gentianaceae). Species 1. Genera 1; only genus, Saccifolium.
Maguire and Pires 1978.
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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, genera included in each family, classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG), and notes on the APG classification.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 10th April 2008. http://delta-intkey.com’.