The families of flowering plants
~ Primulaceae sensu lato.
Habit and leaf form. Low to tall shrubs, or trees, or arborescent (often quite palm-like in habit); not resinous (by contrast with Myrsinaceae). With a basal aggregation of leaves (Deherainia), or with terminal aggregations of leaves (Clavija, Theophrasta), or with a basal aggregation of leaves (Jacquinia being more branched). 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 leaf lamina dorsiventral, or bifacial, or centric. Stomata anomocytic to anisocytic. Hairs present (with uniseriate and peltate forms recorded, also a type with a fantastically branched multicellular head on a uniseriate stalk). Adaxial hypodermis present, or absent. Lamina without secretory cavities. The mesophyll with sclerenchymatous idioblasts (with spicular fibres linking the sclerenchyma situated beneath both upper and lower epidermis); containing crystals. The crystals druses. Minor leaf veins without phloem transfer cells (Deherainia, Jacquinia).
Axial (stem, wood) anatomy. Secretory cavities absent. Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles, or comprising a ring of bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays wide, or mixed wide and narrow.
The wood diffuse porous. The vessels very small; mostly solitary and radially paired. The vessel end-walls simple. The axial xylem without fibre tracheids; with libriform fibres; without septate fibres (or these very rare). The fibres without spiral thickening. The parenchyma very scanty paratracheal (or none). Included phloem absent. The wood not storied.
Reproductive type, pollination. Plants hermaphrodite (usually), or polygamodioecious (Clavija).
Inflorescence, floral, fruit and seed morphology. Flowers solitary (rarely), or aggregated in inflorescences; usually 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, phytochemistry. Sugars transported as sucrose (in Jacquinia). Not cyanogenic. Alkaloids absent (one species). Iridoids not detected. Saponins/sapogenins present. Proanthocyanidins absent. Ellagic acid absent.
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, Theophrasta.
General remarks. See Anderberg et al. (2000) for discussion and references re the Myrsinaceae/Primulaceae genera, of which Theophrastaceae are an outlying component. Samolus was considered by them to be the sister group of Theophrastaceae, and included here by them. Additional to esoteric characters depending on limited sampling (calcium oxalate crystls in leaves, and an aspect of embryology), the present compilation has Theophrastaceae differing from Primulaceae sensu stricto (q.v.) only in the woody habit, fleshy corolla and fruit (berry or drupe).
Illustrations. • Technical details: Jacquinia. • Clavija longifolia: as C. ornata, Bot. Reg. 1764, 1836. • Leaf hairs of Clavija and Jacquinia, with Ardisia (Myrsinaceae)and Aegicerataceae (Aegiceras): Solereder, 1908.
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: 8th December 2015. delta-intkey.com’.