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The families of flowering plants

L. Watson and M.J. Dallwitz

Elaeagnaceae Juss.

Habit and leaf form. Small trees, or shrubs. ‘Normal’ plants to switch-plants (often with shoots reduced to spines). Leptocaul. Mesophytic, or xerophytic (often on steppes or coastal). Leaves alternate (usually), or opposite (rarely); usually spiral; ‘herbaceous’, or leathery; petiolate; non-sheathing; simple; epulvinate. Lamina entire; pinnately veined. Leaves exstipulate. Lamina margins entire. Leaf development not ‘graminaceous’.

General anatomy. Plants with ‘crystal sand’ (commonly), or without ‘crystal sand’.

Leaf anatomy. The leaf lamina typically dorsiventral (but the abaxial mesophyll may tend to palisade-like). Stomata mainly confined to one surface (abaxial); anomocytic. Hairs present (in abundance, covering leaves and shoots); glandular; multicellular. Complex hairs present; usually short- but sometimes long-stalked peltate, or stellate (the plants scaly). The mesophyll containing crystals. The crystals raphides and solitary-prismatic (with various types of acicular crystals and sand predominating, and no druses). Minor leaf veins without phloem transfer cells (Elaeagnus, Hippophaë).

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood ring porous. The vessels small (usualy extremely so in the late wood); almost exclusively solitary. The vessel end-walls simple. The vessels with vestured pits; with spiral thickening. The axial xylem with tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; including septate fibres (all septate, in Petenaea), or without septate fibres. The fibres with spiral thickening, or without spiral thickening. The parenchyma apotracheal (diffuse, sometimes very sparse). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones (commonly), or not stratified. ‘Included’ phloem absent. The wood storied (Hippophaë), or partially storied (VPI).

Reproductive type, pollination. Plants hermaphrodite, or dioecious, or androdioecious, or gynodioecious. Female flowers without staminodes. Gynoecium of male flowers absent (rudiments generally absent). Pollination anemophilous, or entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. The ultimate inflorescence units when flowers aggregated, racemose. Inflorescences axillary; short, fasciculate, spicate or racemose. Flowers fragrant (often), or odourless. Free hypanthium present (constricted above the gynoecium though free from it in female and hermaphrodite flowers, often flat in males). Hypogynous disk present, or absent; when present, of separate members.

Perianth sepaline (apetalous); (2–)4(–6); joined (into a hypanthium tube); 1 whorled; petaloid (often, somewhat), or sepaloid; white, or cream, or yellow. Calyx (the perianth being so interpreted) (2–)4(–6); gamosepalous (basally); blunt-lobed, or entire (rarely). Calyx lobes markedly shorter than the tube to markedly longer than the tube. Calyx regular; valvate (usually), or open in bud (rarely).

Androecium (2–)4, or 8(–12). Androecial members adnate (to the perianth); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (2–)4, or 8(–12); isomerous with the perianth, or diplostemonous; alternisepalous, or alternisepalous and oppositisepalous; erect in bud. Anthers dorsifixed, or basifixed; non-versatile; dehiscing via longitudinal slits; introrse. Pollen grains aperturate; (2–)3(–4) aperturate; colporate; 2-celled.

Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous; seemingly of one carpel; superior (i.e. free, though flower perigynous). Carpel stylate; apically stigmatic; 1 ovuled. Placentation basal. Stigmas dry type; non-papillate; Group II type. Ovules shortly funicled, or sessile; ascending; non-arillate; anatropous; bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Endosperm formation nuclear.

Fruit non-fleshy (within the fleshy hypanthium). The fruiting carpel indehiscent; an achene. Fruit enclosed in the fleshy hypanthium (the latter often drupelike — fleshy outside, bony within). Seeds endospermic (scantily), or non-endospermic. Cotyledons 2 (expanded, fleshy). Embryo achlorophyllous (2/5); straight.

Seedling. Germination phanerocotylar. Nitrogen-fixing root nodules present (commonly), or absent.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Elaeagnus. Anatomy non-C4 type (Elaeagnus). Sugars transported as sucrose (Elaeagnus). Not cyanogenic. Alkaloids present (commonly), or absent. Arbutin absent. Iridoids not detected (? — Gibbs reported a ‘doubtfully positive’ Ehrlich test for Shepherdia). Saponins/sapogenins present (commonly), or absent. Proanthocyanidins present, or absent; when present, cyanidin and delphinidin. Flavonols present; kaempferol and quercetin. Ellagic acid present (5 species, 3 genera). Aluminium accumulation not found.

Geography, cytology. Temperate (mostly), sub-tropical to tropical. Mostly North temperate, but some in Eastern Australia. X = 6, 10, 11, 13.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Elaeagnales. Cronquist’s Subclass Rosidae; Proteales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Rosales.

Species 50. Genera 3; Elaeagnus, Hippophaë, Shepherdia.

Economic uses, etc. The fruit of H. rhamnoides is edible and rich in vitamin C; that of Elaeagnus spp. constitutes ‘Russian’ or ‘wild olive’, ‘goumi’, ‘trebizond date’; and Shepherdia argentea is ‘buffalo- (rabbit-) berry’ or ‘Nebraska currant.

Illustrations. • Le Maout and Decaisne: Elaeagnus angustifolia. • Elaeagnus umbellata var. parvifolia: Bot. Reg. 29 (51), 1843. • Hippophae rhamnoides (B. Ent., 1838). • Hippophae rhamnoides: Eng. Bot. 1245, 1868. • Peltate foliar hair of Hippophae rhamnoides: 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: 15th April 2018.’.