Family Actinidiaceae

Actinidiaceae Van Tiegh.

Including Sauraujeae (Sauraujaceae) J.G. Agardh, Saurauiaceae J.G. Agardh corr. Hutch.

Habit and leaf form. Trees, or shrubs, or lianas. Plants non-succulent. Self supporting, or climbing. Mesophytic. Leaves alternate; spiral; non-sheathing; not gland-dotted; simple. Lamina entire; pinnately veined; cross-venulate. Leaves minutely stipulate. Stipules caducous. Lamina margins entire, or serrate.

General anatomy. Plants with ‘crystal sand’ (dubiously, in the phloem), or without ‘crystal sand’.

Leaf anatomy. Stomata present; anomocytic.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides. Minor leaf veins without phloem transfer cells (Actinidia).

Stem anatomy. Cork cambium present; initially deep-seated, or superficial. Nodes unilacunar (usually), or tri-lacunar. Secondary thickening developing from a conventional cambial ring. Xylem with tracheids; with vessels. Vessel end-walls oblique; simple, or scalariform and simple. Wood parenchyma apotracheal. Pith with diaphragms.

Reproductive type, pollination. Plants hermaphrodite, or monoecious, or dioecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences axillary (sometimes on old wood); usually small cymose clusters. Flowers often bracteolate (with small bracteoles); regular; (4–)5(–7) merous. Free hypanthium absent.

Perianth with distinct calyx and corolla; (8–)10(–14); 2 whorled; isomerous. Calyx (4–)5(–7); 1 whorled; polysepalous; regular; persistent; accrescent (often), or non-accrescent; imbricate. Corolla (4–)5(–7); 1 whorled; polypetalous; imbricate; regular; deciduous.

Androecium (10–)18–100 (usually numerous). Androecial members branched, or unbranched; maturing centrifugally; free of the perianth; all equal; free of one another, or coherent (then variously united at the base, often in five clusters opposite the petals). Androecium exclusively of fertile stamens. Stamens (10–)18–100 (usually many); diplostemonous to polystemonous; erect in bud, or inflexed in bud. Anthers dorsifixed; becoming inverted during development, their morphological bases ostensibly apical in the mature stamens; versatile; dehiscing via pores to dehiscing via short slits (these ostensibly apical), or dehiscing via longitudinal slits. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with more than one middle layer (2 or 3). Tapetum glandular. Pollen shed in aggregates, or shed as single grains; when aggregated, in tetrads. Pollen grains aperturate; 3 aperturate; colporate; 2-celled.

Gynoecium 5–20 carpelled (or more?). Carpels increased in number relative to the perianth. The pistil (4–)5–30 celled (or more). Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary (4–)5–30 locular (or more — equalling the capels). Gynoecium stylate. Styles free to partially joined; often from a depression at the top of the ovary; apical. Stigmas (4–)5–30 (or more); dry type; papillate; Group II type. Placentation axile. Ovules 15–50 per locule (or more - ‘many’); non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium feebly differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids elongated. Hypostase present. Endosperm formation cellular. Embryogeny solanad.

Fruit fleshy, or non-fleshy; dehiscent (when capsular), or indehiscent; a berry, or a capsule (less commonly). Capsules more or less loculicidal. Seeds endospermic. Endosperm oily (or proteinaceous). Seeds small. Cotyledons 2. Embryo achlorophyllous (1/2); straight, or curved. Polyembryony recorded (common).

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Not cyanogenic. Alkaloids present (rarely), or absent. Iridoids detected; ‘Route I’ type (normal). Arthroquinones detected (Actinidia); polyacetate derived. Verbascosides not detected. Proanthocyanidins present; cyanidin, or cyanidin and delphinidin. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid absent (Actinidia). Arbutin absent. Saponins/sapogenins absent. C3. C3 physiology recorded directly in Actinidia, Saurauia.

Geography, cytology. Tropical and Eastern Asia to northern Australia.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Ericales. Cronquist’s Subclass Dilleniidae; Theales. APG (1998) Eudicot; core Eudicot; Asterid; unassigned to Euasterid I or Euasterid II. APG 3 (2009) Order: Ericales.

Species 350. Genera 3; Actinidia, Clematoclethra, Saurauia.

Economic uses, etc. Some edible fruits, including A. chinensis (‘Kiwi fruit’, ‘Chinese gooseberry’), some ornamentals.

Illustrations.
• Actinidia, Clematoclethra (Chittenden).

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