Morus alba L., white mulberry. Small tree, winter–deciduous, in range to 6 m tall; shoots with asymmetric, lobed leaves; latex cloudy.
Stems with ridge from each leaf aging cylindric, somewhat zigzagged, green, puberulent on young and second year axes.
Leaves helically alternate, lobed or unlobed, petiolate, with stipules; stipules 2, attached to stem at node between petiole and continuing shoot, oblong–oblanceolate to oblong and ± keeled, 7.5—10.5 × 2.5—3.3 mm, green with colorless and thin, short–ciliate margins, midvein green and raised on lower surface, lower surface puberulent and short–hairy; petiole channeled base–to–tip, to 35 × 2.5 mm, tough, short–hairy; blade ovate in outline, unlobed to 5(—7)–lobed, with deep, rounded sinuses, < 40—140 × < 40—110 mm, lobing not symmetric and most on leading edge, lateral lobes ± rounded and terminal lobe ovate, cordate at base, principal sinuses > 1/2 to midrib, serrate on margin with teeth not generally overlapping, pinnately veined with all veins raised on lower surface, veins pale, upper surface without hairs and with minute bumps, lower surface with hairs straight radiating to midrib, with domatia along midrib.
Staminate inflorescence raceme, axillary on emerging shoot, often at 5 successive nodes on new shoot, each raceme of 30—50–flowered, cylindric, 20—25 × 7—9 mm, flowers alternate and in small clusters, anthesis from tip of raceme downward, mostly lacking bracts; peduncle to 7 mm long, green, puberulent; pedicel 0.2—0.6 mm long, whitish.
Staminate flower radial, ca. 2.5 mm across; sepals 4, fused at base, boat–shaped and cupped around each filament and anther before anthesis, 2—2.5 mm long, green with colorless margins, short–hairy and often blushed reddish at tip; petals absent; stamens 4, opposite sepals; filaments strongly bent in bud (whiplike), ± 3 mm, glossy pale green, lower portion swollen to somewhat flattened to bent midpoint and tapered to top, spreading–ascending rapidly when released from sepal; anthers basifixed, dithecal, ca. 1.5 mm long, cream–colored, longitudinally dehiscent; pollen white; pistil absent.
Pistillate inflorescence spike, axillary on emerging shoot, at 1–3 successive nodes on new short beginning axillary to a bud scale or the lowermost foliage leaf, spike with 25—35 tightly packed pistils, ca. 5 × 4 mm, pistils helically alternate but appearing in ca. 5 vertical files of 5—8 per file, lacking bracts; peduncle 5—7 mm long, green, puberulent (with some longer straight hairs); rachis mostly hidden by flowers, whitish, with short hairs.
Pistillate flower bilateral, 1 mm across; sepals 4 in opposite decussate pairs, tightly appressed to ovary, outer pair cupped–roundish positioned at edges of ovary, ca. 1 mm, greenish, short–ciliate at top, inner pair thinner and flattened on faces of ovary; stamens absent; pistil 1; ovary superior, ovoid compressed by adjacent flowers, ca. 1 × 1 × 0.6—0.8 mm, green, glabrous, 1–chambered with 1 ovule; style 1 deeply 2–branched, the branches tentaclelike, ca. 1 mm long, green axis and white papillate edges and tapered to tip, curved to coiled (intertwined).
Fruit multiple fruit of berries in ellipsoid cluster, cluster to 23 × 10.5 mm, with 25+ berries, berry compressed ovoid, 3 × 3 × 2 mm, white, with colorless pulp.
Seed obovoid 3–sided.
A. C. Gibson