| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Geissolomataceae Endl.

Habit and leaf form. Small shrubs. Plants non-succulent. Xerophytic. Leaves persistent; opposite; leathery; subsessile to sessile; simple. Lamina entire; pinnately veined. Leaves stipulate. Stipules intrapetiolar (on the petiole); free of one another; minute, vestigial. Lamina margins entire.

Leaf anatomy. The leaf lamina dorsiventral. Mucilaginous epidermis present. Stomata present; mainly confined to one surface (abaxial); anomocytic. The mesophyll without sclerenchymatous idioblasts (by contrast with Penaeaceae); containing crystals (in the mesophyll). The crystals druses.

Axial (stem, wood) anatomy. Young stems somewhat tetragonal in section. Cork cambium present; initially deep-seated. Internal phloem absent. Secondary thickening developing from a conventional cambial ring.

The vessel end-walls oblique; scalariform. ‘Included’ phloem absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal (then on short, axillary branches), or axillary; six bracteate (the bracts in three pairs, persistent); regular; 4 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth sepaline; 4; 1 whorled; petaloid; red to pink (rose). Calyx 4; 1 whorled; shortly gamosepalous; four blunt-lobed (nearly to the base). Calyx lobes markedly longer than the tube. Calyx persistent; imbricate.

Androecium 8. Androecial members free of the perianth to adnate (inserted at the base of the calyx); markedly unequal (the oppositisepalous members longer); free of one another; 2 whorled (4+4). Androecium exclusively of fertile stamens. Stamens 8; diplostemonous; alternisepalous (i.e. the outer cycle alternating with the sepals); filantherous (with slender filaments). Anthers dorsifixed (ellipsoid); versatile; dehiscing via longitudinal slits; tetrasporangiate. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 4 carpelled. Carpels isomerous with the perianth. The pistil 4 celled. Gynoecium syncarpous; synovarious to synstylovarious (the styles free below, but coherent above); superior. Ovary 4 locular (with four grooves and ridges, four lobed); sessile. Gynoecium stylate. Styles 4; partially joined (being coherent above); apical. Stigmas 4. Placentation axile to apical. Ovules 2 per locule; pendulous; collateral; non-arillate; anatropous; bitegmic. Outer integument contributing to the micropyle. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Fruit 4 seeded. Seeds endospermic. Embryo well differentiated (elongate). Cotyledons 2; linear, fleshy. Embryo central, straight. Testa shining.

Physiology, phytochemistry. Aluminium accumulation demonstrated.

Geography, cytology. Cape. Sub-tropical to tropical. Southern Africa.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Hamamelidales. Cronquist’s Subclass Rosidae; Celastrales. APG III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV Order Crossosomatales.

Species 1 (Geissoloma marginata). Genera 1; only genus, Geissoloma.

Illustrations. • Geissoloma marginata: Nat. Pflanzenfam. 3 (1895). • Geissoloma marginata: Lindley.

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: 8th June 2026. delta-intkey.com’.

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