Family Cassythaceae
Cassythaceae Bartl. ex Lindl.~ Lauraceae Habit and leaf form. Lianas to herbs (large and robust to small and herbaceous, parasitic twiners); bearing essential oils (the crushed shoots being faintly aromatic). Switch-plants; with the principal photosynthesizing function transferred to stems. Leaves much reduced. Plants partially parasitic (dodderlike). Parasitic on aerial parts of the host (with haustoria). Perennial. Climbing; stem twiners. Mesophytic. Leaves minute to small; alternate; spiral; membranous; non-sheathing; gland-dotted, or not gland-dotted (?); simple; peltate, or not peltate; exstipulate. Leaf anatomy. The mesophyll with spherical etherial oil cells, or without etherial oil cells (?); containing mucilage cells, or not containing mucilage cells (?). Stem anatomy. Cork cambium absent (?). Nodes unilacunar. Primary vascular tissue in a cylinder, without separate bundles. Internal phloem absent. Secondary thickening developing from a conventional cambial ring (?). ‘Included’ phloem absent. Vessel end-walls simple. Reproductive type, pollination. Plants hermaphrodite. Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes, or in heads, or in umbels, or in panicles. Inflorescences axillary; sessile or pedunculate heads, panicles, spikes, umbels and racemes; without involucral bracts. Flowers minute to small; regular; 3 merous; cyclic; polycyclic. Free hypanthium present (this at first short, but later accrescent). Perianth with distinct calyx and corolla; 6; 2 whorled; isomerous. Calyx 3; 1 whorled; non-fleshy (scale-like); persistent; non-accrescent. Corolla 3; 1 whorled; polypetalous; regular; white, or yellow; fleshy; non-accrescent. Petals sessile. Androecium 12. Androecial members free of the perianth, or free of the perianth and adnate (with outer staminodes adnate to the corolla); free of one another; 4 whorled (whorls of 3). Androecium including staminodes. Staminodes 3–6; internal to the fertile stamens (in 1–2 whorls). Stamens (6–)9; diplostemonous to triplostemonous; somewhat laminar to petaloid (by expansion of the filament and connective), or filantherous. Anthers basifixed; non-versatile; dehiscing by longitudinal valves (cf Lauraceae, opening from the base upwards?); extrorse; bilocular; bisporangiate, or tetrasporangiate, or bisporangiate and tetrasporangiate (?). Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis successive. Anther wall initially with more than one middle layer; of the ‘basic’ type. Tapetum glandular. Pollen grains nonaperturate; 2-celled. Gynoecium 1 carpelled (ostensibly), or 3 carpelled (theoretically). The pistil 1 celled. Gynoecium ostensibly monomerous; of one carpel (or at least, ostensibly so); superior. Carpel stylate; apically stigmatic; 1 ovuled. Placentation apical. Ovules pendulous; apotropous; with dorsal raphe; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Endothelium not differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed, or not formed; not proliferating. Hypostase absent. Endosperm formation cellular. Endosperm haustoria absent. Fruit fleshy. The fruiting carpel indehiscent; baccate. Fruit enclosed in the fleshy hypanthium; 1 seeded. Seeds non-endospermic. Embryo well differentiated. Embryo achlorophyllous; straight. Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Ellagic acid absent. Arbutin absent. Saponins/sapogenins absent. Geography, cytology. Paleotropical, Australian, and Antarctic. Temperate to tropical. Africa, Indonesia, New Guinea, Australia, New Zealand. Supposed basic chromosome number of family: 12. Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Magnoliiflorae; Laurales. Cronquist’s Subclass Magnoliidae; Laurales. APG 3 Order Laurales (as a synonym of Lauraceae). Species 17. Genera 1; only genus, Cassytha. Usually treated as an inconveniently aberrant subfamily of Lauraceae, which seems unnecessary even under cladistic dogma. Illustrations. |
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