Rosa L.

Scientific Description

Common name. Rose. Family Rosaceae.

Habit and leaf form. Shrubs, or lianas, or herbaceous climbers; evergreen, or deciduous. Plants prickly (stems). The spines axial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves; to 3–8 m high. Self supporting, or climbing; scrambling. Leptocaul. Mesophytic. Not heterophyllous. Leaves medium-sized; not fasciculate; alternate; spiral; not decurrent on the stems; ‘herbaceous’; not imbricate; petiolate. Petioles wingless. Leaves non-sheathing; compound; epulvinate; ternate, or pinnate. Leaves pinnately trifoliolate. Leaves imparipinnate. Leaflets 3–15; 1–8 cm long. Lateral leaflets opposite. Leaflets not stipellate; epulvinate; elliptic, or oblong, or ovate, or obovate, or orbicular; rounded at the base; flat; without lateral lobes. Leaflet margins flat. Leaf blades pinnately veined; cross-venulate. Mature leaf blades adaxially glabrous (or nearly so); abaxially glabrous, or pubescent. Leaves with stipules. Stipules intrapetiolar; adnate to the petiole (partly); free of one another; leafy; persistent. Leaf blade margins crenate, or serrate, or dentate; not prickly; flat. Vegetative buds scaly. Leaves without a persistent basal meristem. Vernation conduplicate. Leaf anatomy. Hydathodes absent. Hairs present; glandular hairs present. Unicellular hairs present. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants not viviparous; homostylous. Entomophilous; via beetles, or via hymenoptera, or via lepidoptera.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; not crowded at the stem bases; terminal. Inflorescence few-flowered, or many-flowered. Flowers in corymbs, or in panicles. Inflorescences compound. The terminal inflorescence unit cymose. Inflorescences terminal. Flowers pedicellate. Pedicels terete. Flowers ebracteolate; medium-sized, or large; often fragrant; regular; 5 merous, or 4 merous (rarely). Floral receptacle markedly hollowed. Free hypanthium present; campanulate, or urceolate, or tubular, or globose; extending beyond ovary. Hypogynous disk present; intrastaminal; annular. Perianth with distinct calyx and corolla; 10–50 (numerous in cultivars); 2 -whorled; isomerous, or anisomerous (in cultivars). Calyx present; 5; 1 -whorled; polysepalous. Calyx segments divided, or entire. Calyx spreading; imbricate; exceeded by the corolla; regular; green; non-fleshy; persistent, or not persistent. Sepals triangular. Corolla present; 5–50 (5 in wild types, often numerous in double flowered cultivars); 1 -whorled, or 2 -whorled; polypetalous; imbricate; regular; glabrous abaxially; glabrous adaxially; plain, or with contrasting markings; white, or yellow, or orange, or red, or pink, or purple; deciduous; non-accrescent. Petals obovate; sessile; not hooded; not navicular. Corolla members entire. Androecium present. Androecial members indefinite in number. Androecium 10–100. Androecial members free of the perianth; markedly unequal (the outer whorls longer than the inner); free of one another; 1–15 -whorled. Stamens (1–)20–100; attached on the rim of the hypanthium; all more or less similar in shape; polystemonous; both opposite and alternating with the corolla members; inflexed in bud. Filaments not geniculate; glabrous; filiform. Anthers all alike; dorsifixed; versatile; dehiscing via longitudinal slits; tetrasporangiate. Gynoecium 100 carpelled. Carpels increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous; superior. Carpel stylate; apically stigmatic. Style straight. Stigmatic tissue terminal. Styles united, or free. Carpel 1 ovuled. Placentation apical. Styles simple; not becoming exserted; deciduous; hairy, or hairless. Stigmas capitate. Ovules pendulous; non-arillate; anatropous.

Fruit and seed features. Fruit 0.5–3.5 mm long; stipitate, or subsessile, or sessile; fleshy; yellow, or orange, or red, or black; not hairy; an aggregate. The fruiting carpels coalescing into a secondary syncarp (with small achenes). The fruiting carpel indehiscent; an achene. Fruit enclosed in the fleshy hypanthium; 100 celled. Endocarp not ribbed. Dispersal unit the fruit. Dispersal by mammals, birds and reptiles. Fruit 50 seeded. Seeds 1 per locule. Seeds non-endospermic; minute, or small. Cotyledons 2. Embryo straight; 1 the length of the seed. Testa hard; smooth. Seedling. Cotyledon hyperphyll assimilatory.

Geography, cytology, number of species. World distribution: temperate Northern Hemisphere with the largest concentration of species in the region between China and western Asia, and extending to tropical mountains. Adventive. Australian states and territories: Western Australia, or South Australia, or Queensland, or New South Wales, or Victoria, or Tasmania. South-West Botanical Province. X=7; ploidy levels recorded 2, or 4, or 6, or 8. A genus of ca. 120 species; 5 species in Western Australia; Rosa canina L., Rosa chinensis x moschata Herrm., Rosa chinensis x multiflora Murray, Rosa laevigata Michx., Rosa rubiginosa L.

Economic uses, etc. Attar of roses (rose oil), rose water, vitamin C (from the rose hips); horticulture.

Etymology. From the Latin rosa meaning "pink".