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The families of flowering plants.                                                                                                                                                                

Elaeagnaceae Juss.

                        

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Habit and leaf form. Trees, or shrubs (small). ‘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. Leaves without a persistent basal meristem.

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

Leaf anatomy. Stomata mainly confined to one surface (abaxial); anomocytic. Hairs present. Complex hairs present; peltate, or stellate (the plants scaly).

Minor leaf veins without phloem transfer cells (Elaeagnus, Hippophaë).

Stem anatomy. Cork cambium present; initially superficial. Nodes unilacunar. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones (commonly), or not stratified. ‘Included’ phloem absent. Xylem with tracheids; with libriform fibres; with vessels. Vessel end-walls simple. Vessels with vestured pits. Wood storied (Hippophaë), or partially storied (VPI); parenchyma apotracheal (diffuse, sometimes very sparse).

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 unit(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.

Perianthsepaline (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.

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

Geography, cytology. Temperate (mostly), or 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 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; 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.

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