Pyrus L.

Scientific Description

Common name. Pear. Family Rosaceae.

Habit and leaf form. Trees, or shrubs; deciduous, or evergreen (rarely). Plants spiny, or unarmed. The spines axial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves; to 2–20 m high. 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; simple; epulvinate. Leaf blades entire, or dissected; flat; ovate, or obovate, or elliptic; pinnatifid; pinnately veined; cross-venulate; attenuate at the base, or rounded at the base. Mature leaf blades glabrous, or pilose; adaxially glabrous; abaxially glabrous. Leaves with stipules. Stipules intrapetiolar; free of the petiole; free of one another; leafy; caducous. Leaf blade margins serrate, or dentate, or entire (rarely); not prickly; flat. Vegetative buds scaly. Leaves without a persistent basal meristem. Vernation conduplicate, or involute, or convolute. Leaf anatomy. Hairs present, or absent. 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. Floral nectaries present. Entomophilous; via hymenoptera, or via diptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered. Flowers in racemes, or in corymbs. Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences terminal. Flowers pedicellate; bracteate. Bracts deciduous. Flowers ebracteolate; small, or medium-sized; regular; 5 merous. Floral receptacle markedly hollowed. Free hypanthium present; campanulate, or urceolate. Hypogynous disk present; intrastaminal; annular. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous. Calyx lobes markedly shorter than the tube. Calyx segments entire. Calyx erect, or spreading; hairy; imbricate; exceeded by the corolla; campanulate, or urceolate; regular; green; persistent, or not persistent. Calyx lobes triangular. Corolla present; 5; 1 -whorled; polypetalous; imbricate; regular; glabrous abaxially; hairy adaxially, or glabrous adaxially; plain; white, or pink; deciduous. Petals elliptic, or obovate, or orbicular; clawed; not hooded; navicular. Corolla members entire. Androecium present. Androecial members indefinite in number. Androecium 15–100. Androecial members maturing centripetally, or maturing centrifugally; free of the perianth; all equal, or markedly unequal; free of one another; 1–15 -whorled. Stamens 15–100; attached on the rim of the hypanthium; all more or less similar in shape; triplostemonous, or polystemonous; both opposite and alternating with the corolla members; inflexed in bud. Filaments not geniculate; glabrous; filiform. Anthers all alike; dorsifixed; versatile; tetrasporangiate. Gynoecium 2–5 carpelled. The pistil 2–5 celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; semicarpous; partly inferior, or inferior. Ovary plurilocular; 2–5 locular. Gynoecium stylate. Styles 2–5; free, or partially joined; simple; apical; about as long as the ovary at anthesis, or much longer than the ovary at anthesis; not becoming exserted; persistent; hairless, or hairy (often pubescent below). Stigmas 2–5; 1–2 - lobed; truncate. Placentation basal, or axile. Ovules 1–2 per locule; ascending; non-arillate; anatropous.

Fruit and seed features. Fruit 8–160 mm long; stipitate; falling from the plant before the next growing season; fleshy; green, or yellow, or brown; not hairy; indehiscent; a drupe (pome). The drupes with one stone. Fruit enclosed in the fleshy hypanthium; 2–5 celled; 2–5 locular. Dispersal unit the fruit. Dispersal by animals and birds. Fruit 2–10 seeded. Seeds 1–2 per locule. Seeds reniform; endospermic, or non-endospermic; not compressed (ovoid); small. Cotyledons 2. Testa hard (membraneous); smooth (sometimes with longitudinal striations).

Geography, cytology, number of species. World distribution: Europe, Asia and North America. Adventive. Australian states and territories: Western Australia, or South Australia, or New South Wales, or Victoria, or Australian Capital Territory. South-West Botanical Province. X=17; ploidy levels recorded 3, or 4. A genus of ca. 25 species; 1 species in Western Australia; Pyrus communis L.

Economic uses, etc. Fruit edible; bark has antibacterial properties; timber used for turning, cutlery handles, inlay work and (stained) piano keys; used as street trees in USA and eastern Europe due to high salt-tolerance.

Etymology. From the Latin pirus or pyrus, " a pear tree".