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The families of flowering plants.                                                                                                                                                                

Oliniaceae Arn. ex Sond.

                        

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~Penaeaceae

Habit and leaf form. Much branched, small trees, or shrubs. Leaves opposite; not gland-dotted; simple. Lamina entire; pinnately veined. Leaves vestigially stipulate, or exstipulate. Lamina margins entire. Domatia occurring in the family (Olinia); manifested as pits.

Leaf anatomy. Stomata present; anomocytic, paracytic, and cyclocytic. Hairs present; glandular; unicellular.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals solitary-prismatic.

Stem anatomy. Young stems cylindrical, or tetragonal. Cork cambium present; initially superficial. Nodes unilacunar. Internal phloem present. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem without tracheids; without fibre tracheids; with libriform fibres; with vessels. Vessel end-walls oblique; simple. Vessels with vestured pits. Primary medullary rays narrow. Wood parenchyma scanty paratracheal.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence unit cymose. Inflorescences terminal, or axillary. Flowers small; regular; 4–5 merous; cyclic. Free hypanthium present.

Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx 4, or 5 (represented only by a narrow rim on the hypanthium); 1 whorled; more or less polysepalous; usually more or less 4–5 lobulate, or blunt-lobed, or toothed; regular; not persistent (deciduous). Corolla 4, or 5; 1 whorled; alternating with the calyx (facilitating the identification of the latter); polypetalous; imbricate; regular. Petals spathulate.

Androecium 8–10, or 12–15. Androecial members free of the perianth (on the hypanthium); markedly unequal; free of one another; 2 whorled, or 3 whorled. Androeciumincluding staminodes. Staminodes 4–10; external to the fertile stamens;petaloid, or non-petaloid (comprising a set of hairy, incurved, scalelike, coloured or white antesepalous members alternating with the petals and on the same radii as the fertile stamens, and a set of small antepetalous staminodes (which may be obsolete) alternating with them). Stamens 4, or 5; isomerous with the perianth; oppositisepalous; alternating with the corolla members; filantherous (the filaments short, recurved). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; bilocular (the thecae distinctly separated on the thickened connective). Endothecium developing fibrous thickenings. Anther wall initially with one middle layer. Tapetum glandular (?). Pollen shed as single grains. Pollen grains aperturate; 3 aperturate, or 6 aperturate; colporate, or colpate and colporate (the colpi alternating with three ‘pseudocolpoid grooves’).

Gynoecium (3–)4 carpelled, or 5 carpelled. Carpels reduced in number relative to the perianth to isomerous with the perianth. The pistil (3–)4–5 celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary (3–)4 locular, or 5 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1; capitate. Placentation axile. Ovules (2–)3 per locule; pendulous; apotropous; superposed; hemianatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3 (small); not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear.

Fruit fleshy; indehiscent; a drupe (or rather, inferior-drupaceous). The drupes with one stone (one seed in each locule). Fruit 3–5 seeded. Seeds non-endospermic. Embryo well differentiated. Cotyledons 2 (spirally twisted or irregularly folded).

Physiology, biochemistry. Cyanogenic. Cynogenic constituents phenylalanine-derived. Aluminium accumulation not found.

Geography, cytology. Paleotropical and Cape. Sub-tropical to tropical. West and South Africa. X = 10.

Taxonomy.Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Myrtales (as a synonym of Penaeaceae?).

Species 10. Genera 1; only genus, Olinia.

 Illustrations:

  • Technical details: Olinia.
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