XXII. ROSACEÆ.
Trees, shrubs and herbs, with watery juices, terete branchlets, scaly buds, and alternate leaves (opposite in Lyonothamnus), with stipules. Flowers perfect; calyx 5-lobed; petals 5 (0 in Cercocarpus), imbricated in the bud, inserted with the numerous distinct stamens on the edge of a disk lining the calyx-tube; anthers introrse (extrorse in Vauquelinia), 2-celled, the cells opening longitudinally; ovary superior in Lyonothamnus and Heteromeles, often partly superior in Amelanchier; ovules 2 in each cell (1 in Cowania and Cercocarpus, 4 in Lyonothamnus), anatropous. Seeds without albumen (albuminous in Lyonothamnus and Cowania). A family of about ninety genera chiefly confined to the temperate parts of the world and producing many of the most valuable fruits, including the apple, pear, quince, strawberry, raspberry, and blackberry. The six tribes into which the genera of the family are grouped, have arborescent representatives in North America.
CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT GENERA.
Tribe 1. Spiræoideæ. Fruit a woody capsule. Flowers in terminal cymose corymbs; calyx-lobes persistent; ovary 5-celled; ovules ascending; mature carpels adherent below and opening down the back; albumen 0; leaves simple.1. [Vauquelinia.] Flowers in terminal corymbs; calyx-lobes deciduous; ovary 2-celled; ovules 4 in each cell, pendulous; mature carpels opening on the ventral and partly on the dorsal suture; albumen thin; leaves opposite, simple or pinnately divided.2. [Lyonothamnus.] Tribe 2. Pomoideæ. Fruit a pome composed of the thickened and succulent calyx-tube inclosing the papery or bony carpels; stipules free from the petioles. Mature carpels papery. Carpels as many as the styles. Flowers in few-flowered terminal racemes on short spur-like lateral branchlets; ovary 3—5-celled; styles more or less united below; leaves simple; winter-buds small.3. [Malus.] Flowers in broad compound terminal cymes; ovary 2—4, usually 3-celled; styles distinct; fruit subglobose; leaves unequally pinnate; winter-buds large.4. [Sorbus.] Flowers in large terminal corymbose panicles; ovary nearly superior, 2-celled; styles distinct; fruit obovoid.5. [Heteromeles.] Carpels becoming at maturity twice as many as the styles; flowers in erect or nodding racemes; ovary inferior or partly superior; styles 2—5, more or less united below; fruit subglobose or pyriform; leaves simple, deciduous.6. [Amelanchier.] Mature carpels bony; flowers in terminal cymose corymbs; ovary 1—5-celled; styles distinct; fruit globose to pyriform; leaves simple, deciduous.7. [Cratægus.] Tribe 3. Dryadæ. Calyx-tube turbinate, campanulate or hemispheric; petals 5; ovary composed of 1 or several carpels; fruit an akene tipped with the elongated plumose style. Flowers terminal on short branchlets, solitary; calyx-tube turbinate; carpels 5—12; leaves alternate, toothed or pinnatifid.8. [Cowania.] Tribe 4. Cercocarpæ. Calyx-tube salver-shaped; petals 0; ovary composed of a single carpel; fruit an akene, tipped with the elongated plumose style. Leaves alternate, simple, entire or serrate.9. [Cercocarpus.] Tribe 5. Prunoideæ. Fruit a 1-seeded drupe; ovary 1-celled; style terminal; ovules pendulous. Flowers in fascicled umbels, or racemes; leaves simple, deciduous or persistent.10. [Prunus.] Tribe 6. Chrysobalanoideæ. Fruit a 1-seeded drupe; ovary 1-celled; style lateral, ovules ascending. Flowers in axillary or terminal cymose panicles; leaves simple, persistent.11. [Chrysobalanus.]