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The families of flowering plants

L. Watson and M.J. Dallwitz

Penaeaceae Guillemin

Excluding Crypteroniaceae, Oliniaceae, Rhynchocalycaceae.

Habit and leaf form. Shrubs (typically small, often ericoid). Leaves opposite (decussate); leathery; imbricate (often), or not imbricate; petiolate to sessile; simple. Lamina entire; pinnately veined (with a continuous marginal vein). Leaves stipulate (the stipules vestigial), or exstipulate.

Leaf anatomy. The leaf lamina dorsiventral (mostly), or bifacial, or centric. Stomata present, or absent (infrequent); when present, mainly confined to one surface (abaxial), or on both surfaces; anomocytic, or anisocytic (sometimes with peg-like projections into the subsidiaries, see illustration). Hairs present, or absent (rare); when present, eglandular; unicellular. Unicellular hairs simple. Complex hairs absent. The mesophyll with sclerenchymatous idioblasts (see illustration); containing crystals, or without crystals. The crystals when found, druses.

Axial (stem, wood) anatomy. Cork cambium in Penaea, present; initially deep-seated (in the pericycle). Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; bicollateral. Internal phloem universally present. Cortical bundles present, or absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The vessel end-walls simple. The axial xylem with tracheids; with fibre tracheids. ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary to aggregated in ‘inflorescences’ (occasionally paired, often crowded); axillary (with the upper leaves); bracteate (the bracts often coloured); bracteolate (the bracteoles opposite, in one or more pairs); regular; 4 merous; cyclic; tricyclic. Free hypanthium present. Hypogynous disk absent.

Perianth sepaline (but the hypanthium and calyx often coloured like a corolla); 4; 1 whorled; sepaloid, or petaloid. Calyx 4; 1 whorled; polysepalous (as lobes on the hypanthium); regular; persistent (with the hypanthium); valvate.

Androecium 4. Androecial members free of the perianth (attached to the hypanthium); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 4; isomerous with the perianth; alternisepalous; filantherous (the filaments very short). Anthers basifixed (the connective much expanded, thickly laminar, often much longer than the ventral or marginal, frequently well separated thecae); dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged (?). Pollen shed as single grains. Pollen grains aperturate; 3–5 aperturate, or 6–10 aperturate; colpate and colporate (the colpi alternating with colpoid grooves).

Gynoecium 4 carpelled. Carpels isomerous with the perianth. The pistil 4 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 4 locular; sessile. Gynoecium stylate. Styles 1; apical. Stigmas 1; capitate or four-lobed. Placentation basal to axile, or axile, or axile to apical. Ovules 2–4 per locule; pendulous, or ascending, or pendulous and ascending; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Penaea-type. Polar nuclei fusing prior to fertilization. Endosperm formation nuclear. Embryogeny asterad.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal (surrounded by the persistent hypanthium). Seeds more or less non-endospermic. Embryo well differentiated. Cotyledons 2 (very small).

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. Aluminium accumulation not found.

Geography, cytology. Cape. Sub-tropical. Southernmost Africa. X = 11, 12.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Myrtales.

Species 25. Genera 7; Brachysiphon, Endonema, Glischrocolla, Penaea, Saltera, Sonderothamnus, Stylapterus.

Illustrations. • Penaea mucronata, Stylapterus sp. and Saltera sp. (as Sarcocolla vulgaris): Lindley. • Saltera sarcocolla, as Sarcocolla squamosa: Thonner. • Leaf anatomy of Penaea: P. mucronata (TS) and P. myrtoides (epidermis): Solereder, 1908.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.