13. Fragaria L. (strawberry)

Plants perennial herbs with short, stout rhizomes. Stems absent, but slender, prostrate to arched stolons present, these rooting at the tip, lacking spines and thorns, hairy, usually with 1 scalelike leaf toward the midpoint, this 3–10 mm long, simple, linear to narrowly lanceolate, entire, often wrapped around the stolon at the base. Leaves in rosettes at the rhizome tip and where the stolons root, long-petiolate, the petioles usually sparsely to densely hairy. Stipules 10–20 mm long, herbaceous, oblong-lanceolate to ovate, narrowed or tapered to a sharply pointed tip, fused to the petiole above the middle, glabrous or more commonly hairy, especially along the midvein and margins, green to orangish brown and often purple-tinged, persistent after the leaves are shed. Leaf blades broadly triangular in outline, divided into 3 more or less similar leaflets (lateral leaflets sometimes somewhat symmetric at the base; seedling leaves simple), these elliptic to obovate, rounded or bluntly pointed at the tip, narrowed at the base, the margins toothed or scalloped, sparsely to densely pubescent with appressed to spreading, silky hairs, at least on the undersurface. Inflorescences open few-flowered panicles, rarely reduced to a solitary flower, sometimes appearing umbellate or racemose, produced on long usually hairy stalks from the leaf axils at the rhizome tip, the branch points with stipule-like bracts, the basal branch point with an additional 1 or 2 reduced leaflike bracts. Flowers short- to long-stalked, perigynous, the hypanthium saucer-shaped, lacking a nectar disc, hairy, each flower with 5 bractlets alternating with the sepals (the calyx thus appearing 10-parted), these similar to but somewhat narrower than the sepals, linear-lanceolate to lanceolate, tapered to the sharply pointed tip, not becoming noticeably enlarged at fruiting. Sepals 5, sometimes slightly unequal in length, ascending to reflexed, lanceolate to broadly lanceolate, tapered to a sharply pointed tip, the margins often with a pair of small teeth or lobes near the tip, sparsely to moderately hairy, not noticeably enlarged at fruiting. Petals 5, obovate, white. Stamens 20–35, some of the outer ones sometimes reduced to staminodes, the anthers yellow. Pistils numerous, densely covering the surface of the obconic or columnar receptacle. Ovary superior, glabrous, with 1 locule, with 1 ovule. Style 1 per pistil, attached laterally near the ovary base, persistent at fruiting, the stigma disc-shaped. Fruits achenes, 0.9–1.5 mm long, moderately spaced (not overlapping) in shallow pits or on the surface of the enlarged, top-shaped to ovoid or ellipsoid, bright red receptacle, asymmetrically ovate in outline, glabrous, shiny, yellowish brown to dark brown, with 1 seed. About 20 species, North America, Hawaii, South America, Europe, Asia.

The garden strawberry, F. ×ananassa Duchesne ex Rozier, is a commercially important crop plant that was initially developed in Europe during the first half of the eighteenth century from spontaneous hybrids of the American species F. chiloensis (L.) Mill. and F. virginiana Mill. that arose from plants cultivated there (K. R. Robertson, 1974; Staudt, 1999). Extensive continuing breeding programs have given rise to numerous strawberry cultivars differing in yield, ripening times, and flavor, but also in such morphological characters as calyx and bractlet size and the size and shape of the “berry” (which is actually a greatly expanded receptacle covered with tiny achenes). Fragaria ×ananassa rarely escapes from cultivation in Missouri (Steyermark, 1963; Mühlenbach, 1979). It differs from the two native species in the generally larger size of the plants; its larger flowers (petals 10–15 mm long), sometimes with extra sepals and petals, and more foliacous sepals; and its larger fruits (1.5–3.0 cm long); as well as in several subtle characters of leaf texture and pubescence.