3. Prunus armeniaca L. (apricot)

Armeniaca vulgaris Lam.

Pl. 537 k, l; Map 2473

Plants trees, to 10 m tall, not suckering. Branches unarmed. Twigs glabrous, producing pseudoterminal winter buds (these usually in a cluster of 2 or 3 at the tip). Petioles (12–)20–45 mm long, glabrous or somewhat hairy toward the tip, with 1–5 stout, stalked glands near the tip and/or along the basal portions of the blade margins. Leaf blades (3–)5–9 cm long, (2–)4–8 cm wide, less than 2 times as long as wide, ovate to broadly ovate or slightly heart-shaped, rounded to broadly angled to occasionally truncate or shallowly cordate at the base, angled or short-tapered to a sharply pointed tip, the margins simply or doubly toothed, the more or less blunt and usually at least slightly incurved teeth gland-tipped, the upper surface glabrous or occasionally with scattered, short, stiff hairs, the undersurface with main veins hairy, mostly in the basal half of the leaf or more commonly with only small tufts of hairs in the axils of the main veins. Inflorescences produced before the leaves develop, of solitary flowers per bud (2 or more buds may be clustered at some nodes), the flower stalks absent or to 3 mm long, hairy. Flowers with the hypanthum 4–6 mm long, narrowly bell-shaped, glabrous or sparsely hairy. Sepals 4–6 mm long, reflexed at flowering, oblong-ovate, the margins nearly entire, with at most a few glandular teeth, the inner surface sparsely hairy. Petals 8–12 mm long, broadly elliptic to nearly circular, pink or pinkish-tinged while in bud, but becoming white at flowering. Fruits 25–60 mm long, broadly ellipsoid to more or less globose, somewhat flattened, shallowly to deeply longitudinally grooved on 1 side, the surface yellow to orange, sometimes tinged with red, densely and minutely hairy, but often becoming nearly glabrous at maturity, the fleshy layer well-developed, the stone ellipsoid to more or less globose, strongly flattened, the surface more or less smooth. 2n=16. March–April.

Introduced, uncommon, known thus far only from Franklin and Stoddard Counties and the city of St. Louis (native of Asia; introduced sporadically in the northeastern and western U.S.; Canada). Railroads and open, disturbed areas.

Typically, the leaf blades of P. armeniaca are glabrous, except for tufts of short, stiff hairs in the axils of the main veins toward the base of the undersurface. However, some of the North American material has the hairs extending up the midvein or other main veins and in a few specimens the upper surface has scattered, minute, stiff, sharply pointed hairs. These differences undoubtedly are an indirect result of plant breeding for various fruit variants in different cultivars.

Apricots are popular fruits when dried, canned, or used in jams and preserves. They also are sold as fresh fruits. This species was first reported for Missouri by Mühlenbach (1979) from the St. Louis railyards.