Family Stachyuraceae

Stachyuraceae J.G. Agardh

Habit and leaf form. Small trees, or shrubs, or lianas. Self supporting, or climbing. Leaves evergreen, or deciduous; alternate; ‘herbaceous’, or leathery; petiolate; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves stipulate. Stipules free of one another; caducous (small, linear-lanceolate). Lamina margins serrate (or serrulate).

Leaf anatomy. Stomata present; mainly confined to one surface (abaxial); anomocytic.

The mesophyll without sclerenchymatous idioblasts; containing calcium oxalate crystals. The mesophyll crystals druses. Minor leaf veins without phloem transfer cells.

Stem anatomy. Cork cambium present; initially superficial. Nodes tri-lacunar. Secondary thickening developing from a conventional cambial ring. Xylem with tracheids; with vessels. Vessel end-walls scalariform. Wood parenchyma apotracheal.

Reproductive type, pollination. Plants hermaphrodite, or polygamomonoecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; pendulous, in racemes, or in spikes. The ultimate inflorescence unit racemose. Inflorescences terminal, or axillary; pendulous racemes or spikes. Flowers bi- bracteolate (the bracteoles connate); small; regular; 4 merous (throughout); cyclic; polycyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium absent.

Perianth with distinct calyx and corolla; 8; 3 whorled; isomerous. Calyx 4; 2 whorled (2+2); polysepalous; regular; much imbricate. Corolla 4; 1 whorled; polypetalous (the petals connivent); imbricate; regular. Petals sessile.

Androecium 8. Androecial members free of the perianth; free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 8; diplostemonous; filantherous (the filaments subulate). Anthers appearing versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen grains aperturate; 3(–4) aperturate; (tri-) colporate (occasionally 4-ruporate); 2-celled.

Gynoecium 4 carpelled. Carpels isomerous with the perianth. The pistil 1 celled, or 4 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular, or 4 locular (4-locular at the base, but above and for most of it length the partitions, though deeply intruded, are not united in the middle). Gynoecium shortly stylate. Styles 1; apical. Stigmas 1; obscurely 4 lobed; capitate to subpeltate; wet type; papillate; Group I type. Placentation parietal (above); axile (below). Ovules 30–50 per locule (‘numerous’); arillate; anatropous; bitegmic; crassinucellate. 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 pear-shaped. Endosperm formation nuclear.

Fruit fleshy; indehiscent; a berry (rather firm and dry, 4-locular); many seeded. Seeds endospermic. Endosperm oily (and proteinaceous). Seeds small. Embryo well differentiated. Cotyledons 2 (flat). Embryo straight.

Physiology, biochemistry. Not cyanogenic. Iridoids not detected. Proanthocyanidins present, or absent; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid present. Arbutin absent. Aluminium accumulation not found.

Geography, cytology. Holarctic. Temperate to tropical. Eastern Asia - Himalayas to Formosa and Japan.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Theiflorae (?); Theales (?). Cronquist’s Subclass Dilleniidae; Violales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Crossosomatales.

Species 10. Genera 1; only genus, Stachyurus.

Illustrations.
• Stachyurus (Chittenden).