The families of flowering plants
~ Primulaceae sensu lato
Habit and leaf form. Low to tall shrubs, or trees; not resinous (by contrast with Myrsinaceae). Leaves pseudo- whorled (clustered towards the branch tips), or alternate; leathery (often with capitate glands); petiolate; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate, or dentate (often pungent tipped and spiny-toothed).
Leaf anatomy. The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses. Minor leaf veins without phloem transfer cells (Deherainia, Jacquinia).
Stem anatomy. Nodes unilacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. Included phloem absent. Xylem with libriform fibres; with vessels. Vessel end-walls simple. Primary medullary rays wide. Wood parenchyma scanty or none.
Reproductive type, pollination. Plants hermaphrodite (usually), or polygamodioecious (Clavija).
Inflorescence, floral, fruit and seed morphology. Flowers solitary (rarely), or aggregated in inflorescences; in racemes, or in corymbs, or in fascicles. Inflorescences terminal (usually), or axillary (rarely); racemes, corymbs or panicles. Flowers often showy, small to large; regular; (4–)5 merous; cyclic; tetracyclic. Free hypanthium present (slight?), or absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx (4–)5 (gland dotted or streaked); 1 whorled; polysepalous (usually), or gamosepalous (basally connate in Clavija); regular; persistent; imbricate. Corolla (4–)5; 1 whorled; gamopetalous (with a short tube); lobes imbricate; rotate, or urceolate, or funnel-shaped; regular; white to yellow, or pink (gland dotted or streaked); somewhat fleshy.
Androecium 8, or 10. Androecial members adnate; free of one another, or coherent (the filaments of the fertile members sometimes connate into a tube); sometimes 1 adelphous; 2 whorled. Androecium including staminodes. Staminodes (4–)5; external to the fertile stamens; petaloid, or non-petaloid (then glandular). Stamens (4–)5; inserted near the base of the corolla tube (the staminodes attached somewhat higher); isomerous with the perianth; alternisepalous (the higher-inserted (= outer), staminodial whorl alternating with the corolla lobes); opposite the corolla members; filantherous. Anthers dehiscing via longitudinal slits; extrorse, or introrse; tetrasporangiate; appendaged (via a produced connective), or unappendaged. Pollen grains aperturate; 3 aperturate; colporate; 2-celled (in Clavija and Jacquinia).
Gynoecium (4–)5 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular (the cavity filled with mucilage); sessile. Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stigmas 1; punctate, discoid or crateriform, sometimes shallowly lobed; wet type, or dry type; papillate (when wet), or non-papillate (when dry); Group II type, or Group III type. Placentation stipitate free central (mostly), or basal (the central column sometimes reduced). Ovules in the single cavity 25–100 (more or less numerous); ascending; anatropous, or campylotropous, or hemianatropous; bitegmic; tenuinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked. Endosperm formation nuclear.
Fruit fleshy (usually), or non-fleshy (sometimes almost dry); indehiscent; a berry (usually), or a drupe (seldom). The drupes with one stone (1-seeded). Fruit 1–100 seeded (i.e. to many). Seeds copiously endospermic. Endosperm oily. Seeds with amyloid. Embryo well differentiated (rather large). Cotyledons 2. Embryo straight. Testa orange, or yellow, or red.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent (one species). Iridoids not detected. Proanthocyanidins absent. Ellagic acid absent. Saponins/sapogenins present. Sugars transported as sucrose (in Jacquinia).
Geography, cytology. Neotropical. Sub-tropical to tropical. Tropical America, West Indies. N = 18. Supposed basic chromosome number of family: 18.
Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgrens Superorder Primuliflorae; Primulales. Cronquists Subclass Dilleniidae; Primulales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales (as a synonym of Primulaceae?).
Species 110. Genera 5; Clavija, Deherainia, Jacquinia, Neomezia, Theophrastia.
General remarks. See Anderberg et al. (2000) for discussion and references re the Myrsinaceae/Primulaceae genera, of which Theophrastaceae are an outlying component. Samolus is considered by them to be the sister group of Theophrastaceae, and is included here by them.
Illustrations. • Technical details: Jacquinia. • Clavija longifolia: as C. ornata, Bot. Reg. 1764, 1836.
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’.