Flowering Plants: Nightshades to Mistletoe

Convolvulacea -- Morning-Glory Family

72 I NIGHTSHADES TO MISTLETOE 35· Petunia violacea (Violet Petunia). a. Habit, X V2. b. Fruit, X 1. c. Seed, X 30. purple or variegated, funnelform, the tube s-g em long, the limb 3-7 em across; capsule ovoid. ~,---,-,--,.,. COMMON NAME: Garden Petunia. HABITAT: Waste ground. RANGE: Horticultural plant; rarely escaped in North America. ILLINOIS DISTRIBUTION: Scattered in Illinois. The garden petunia is thought to be a hybrid between '----'-----'- J"T?' P. axillaris and P. violacea, although it has flowers larger than either. Numerous color variations have been developed . The flowers bloom from June to August. CONVOLVULACEAE-MORNING-GLORY FAMILY Herbs, shrubs, or trees, sometimes twining, sometimes with latex; leaves alternate, simple, without stipules; inflorescence cymose, or Petunia I 73 36. Petunia X hybrida (Garden Petunia). a. Habit, X%. b. Leaf variation, X%. 74 I NIGHTSHADES TO MISTLETOE the flower solitary; flowers perfect, actinomorphic, bracteate; sepals 5, usually free; corolla mostly tubular, 5-lobed or entire; stamens 5, free, attached to the base of the corolla tube; disk often present; pistil1, the ovary superior, 2-locular, with 1-2 ovules per locule on axile placentae; fruit a capsule. This family contains about fifty genera and thirteen hundred species. The greatest concentration of species is in tropical America and tropical Asia. The Convolvulaceae are related to the Polemoniaceae, differing by their twining habit, their latex, their free sepals, and their bicarpellate ovary with 1-2 ovules per locule. They differ from the oftenincluded Cuscutaceae by possessing chlorophyll. There are a number ofgarden ornamentals in the family. Several species of Ipomoea, the morning-glory, are grown for their large, handsome flowers. Another Ipomoea, I. batatas L., is the sweet potato. KEY TO THE GENERA OF Convolvulaceae IN ILLINOIS 1. Corolla rotate, usually blue; stigmas 4 ------------------------- 6. Evolvulus 1. Corolla salverform, funnelform, or nearly campanulate, variously colored ; stigmas 1-2 --------------------------------------- 2 2. Leaves linear, up to 3 (--6) mm broad; style deeply 2-cleft -------- ------------------------------------------ 1. Stylisma 2. Leaves elliptic to oblong to ovate, usually at least 6 mm broad; style undivided, although the stigmas sometimes lobed ____________ 3 3· Flowers scarlet_________________________________ 5· Ipomoea 3· Flowers white, blue, or purple, never scarlet__________________ 4 4· Bracts large and foliaceous, sometimes concealing the calyx ____ 5 4· Bracts small, never exceeding the calyx, or absent____________ 6 5· Flowers in headlike clusters; calyx long-hirsute ____ 2. ]acquemontia 5. Flower solitary or 2-4 in a group; calyx glabrous or pubescent, not longhirsute -------------------------------------- 4· Calystegia 6. Sepals up to 8 mm long; stigmas 2, linear ------- 3· Convolvulus 6. Sepals 10 mm long or longer; stigmas 1 or, if 2, capitate --------- ------------------------------------------ 5· Ipomoea 1. Stylisma Raf.-Stylisma Herbaceous perennial from thickened crowns or rhizomes; stems prostrate or twining; leaves alternate, simple, entire; inflorescence cymose, axillary; flowers perfect, actinomorphic, subtended by 2 Stylisma I 75 bracteoles; sepals 5, free; corolla funnelform, more or less entire; stamens 5, free; pistil 1, the ovary superior, 2-locular, surrounded by a basal disk, with ovules 2 per locule; styles deeply 2-cleft; fruit a capsule, with 1-4 seeds. Stylisma is a genus of six species of temperate North America. Our species is sometimes placed in the genus Breweria, but Myint, who revised the genus Stylisma in 1966, has given reasons for recognizing Stylisma as the valid name. Only the following taxon occurs in Illinois. 1. Stylisma pickeringii (Torr.) Gray var. pattersonii (Fern. & Schuh.) Myint, Brittonia 18:114. 1966. Fig. 37· Breweria pickeringii (Torr.) Gray var. pattersoni Fern. & Schuh. Rhodora 51:42, pl. 1129. 1949· Stylisma pattersoni (Fern & Schuh.) G. N. Jones in Jones & Fuller, Vase. Pl. Ill. 387. 1955. Perennial herb; stems prostrate or trailing, minutely pubescent, to 2 m long; leaves linear, acute to obtuse at the apex, cuneate to the sessile or subsessile base, entire, minutely pubescent, to 7 em long, to 3 (-6) mm wide; flowers cymose, 1-5 per inflorescence, the central ones often sessile, the lateral ones on pedicels to 2 em long, each subtended by a pair offoliar bracts about as long as or slightly longer than the sepals; sepals 5, free, oval-lanceolate, acute or subacute , hoary-pubescent, 4-6 mm long; corolla to 1.8 em long, white, funnelform, the margin more or less entire; stamens 5, free, partly exserted; ovary densely villous; style deeply 2-cleft, the branches 1.0-1.5 mm long, unequal; stylopodia 1-2 mm long; capsule ovoid, pubescent, to about 1 em long, 2-seeded. COMMON NAME...