Rosaceae

A cosmopolitan family of perennial shrubs, trees, and non-woody plants that is most abundant in the Northern Hemisphere; includes many food plants (Apple, Blackberry, Cherry, Plum, Raspberry, Saskatoon Berry, Strawberry) and showy ornamentals (Roses, Flowering Crab, Flowering Quince, Hawthorn, Lady’s-mantle, Mountain Ash, Ninebark, Queen-of-the-Prairie); about 3/4 of its genera contain woody species. Both flowers and fruits are often needed to accurately identify many of the plants in this family. Hybridization is unusual in flowering plants, but relatively common between species in different genera closely related to Apples (e.g., Chokeberry and Mountain Ash). Serviceberries, Hawthorns, Roses and Blackberries can be extremely difficult to identify to species, since they often hybridize with other related species, produce seeds asexually, may have three or more complete sets of chromosomes, and other challenges.

Plants often bearing showy flowers that have 5 sepals amd 5 petals, are symmetrical in all directions (radially), and have a cup-shaped, cylindrical or flat floral tube (hypanthium) at their base, this tube edged with many stamens, a nectar ring on the inside and often enlarging and sometimes becoming fleshy in fruit;Arrangement of flowers is varied, may be solitary or clustered (racemes, corymbs, panicles, spikes, etc.). Flowering in some species occurs before leaves have fully expanded. Pollen and seeds usually produced by the same flowers, but sometimes on separate flowers on the same plant. Large or small bracts in the vicinity of the 5 sepals may give the erroneous impression that there are 10. Petals usually separate, overlapping, often narrowed at the base, rarely absent. Stamens frequently 15 or more, but sometimes 10 or fewer, often in multiples of 5, rarely fewer than twice the number of petals. Stalks of stamens separate or fused to the nectar ring at the base. Carpels 1 to many, separate or fused, sometimes attached to the floral tube, ovary with 1 to 5 chambers, may be above (superior) or below (inferior) the point at which the other flower parts are attached, styles the same number as carpels.

Fruit an achene that may be exposed (Strawberry) or enclosed within the floral tube (Rose), a capsule (Spiraea), stone-fruit (Cherry), aggregate of coherent stone fruits (Blackberriy), or pome (e.g., Apple, with a soft fleshy outer part surrounding a papery or cartilagenous structure containing the seeds).

Leaves usually alternate and/or whroled, usually with stipules and commonly with gland-tipped teeth. Leaves of almost all non-woody species are deeply lobed or compound, while many of the woody species have simple leaves. Hairs, if present anywhere on the plant, typically simple, sometimes glandular, occasionally star-shaped (stellate). Plants sometimes with thorns and/or prickles. Often produce cyanide (e.g., in all parts of the Cherry plant except for the fleshy part of the fruit), but not alkaloids.