4a. Umbel sessile (4-8 dm. high; flowers green, summer) =Green Milkweed, Acerates viridiflora.=

4b. Umbel peduncled --5.

5a. Leaves linear or narrowly linear-lanceolate (4-8 dm. high; flowers greenish-white, summer) =Green Milkweed, Acerates floridana.=

5b. Leaves lanceolate or broader (flowers in summer) --6.

6a. Leaves p.u.b.escent beneath --7.

6b. Leaves glabrous or nearly so --10.

7a. Flowers brilliant orange (3-6 dm. high) =b.u.t.terfly Weed, Asclepias tuberosa.=

7b. Flowers red or purple --8.

8a. Reflexed lobes of corolla merely purple-tinged (1-2 m. high) =Milkweed, Asclepias syriaca.=

8b. Reflexed lobes of corolla bright-red or purple --9.

9a. The erect hoods of each flower about 5 mm. long (7-12 dm. high) =Milkweed, Asclepias purpurascens.=

9b. The erect hoods of each flower about 3 mm. long (6-10 dm. high) =Swamp Milkweed, Asclepias incarnata var. pulchra.=

10a. Leaves broadly rounded and almost sessile at base (flowers purplish) --11.

10b. Leaves narrowed at the base, distinctly petioled (8-15 dm.

high) --12.

11a. Umbel solitary, terminal and erect on a long peduncle (4-8 dm.

high) =Milkweed, Asclepias amplexicaulis.=

11b. Umbels terminal or lateral, bent toward one side (7-12 dm. high) =Milkweed, Asclepias sullivantii.=

12a. Corolla (not hoods) red (1-2 m. high) =Swamp Milkweed, Asclepias incarnata.=

12b. Corolla (not hoods) greenish (8-15 dm. high) =Milkweed, Asclepias exaltata.=

CONVOLVULACEAE, the Morning Glory Family

Twining or trailing herbs (except one species), with regular flowers; sepals 5; corolla 5-angled or 5-lobed; stamens 5, attached to the corolla; ovary superior, 2-3-celled.

1a. Plants with green foliage and conspicuous flowers (summer) --2.

1b. Leafless brown or yellow plants, with very small flowers (Dodder) --7.

2a. Style divided at the top into linear or oblong stigmas (flowers white or pink) (Bindweed) --3.

2b. Style not divided at the top; stigmas sessile, capitate (Morning Glory) --6.

3a. Stem erect; leaves rounded or somewhat cordate at base, not hastate or sagittate (1-3 dm. high) =Bindweed, Convolvulus spithamaeus.=

3b. Stem trailing or twining; leaves sagittate or hastate --4.

4a. Calyx almost concealed by two large heart-shape bracts --5.

4b. Bracts at base of calyx none =Bindweed, Convolvulus arvensis.=

5a. Leaves triangular-hastate, with sharp basal lobes =Bindweed, Convolvulus sepium.=

5b. Leaves oblong-ovate, the basal lobes obtuse =Bindweed, Convolvulus sepium var. p.u.b.escens.=

6a. Stem smooth or nearly so; ovary 2-celled (flowers white) =Wild Potato Vine, Ipomoea pandurata.=

6b. Stem with reflexed hairs; ovary 3-celled (flowers of various colors) =Morning Glory, Ipomoea purpurea.=

7a. Introduced weed, growing as a parasite on clover =Dodder, Cuscuta epithymum.=

7b. Native species, on various shrubs and herbs --8.

8a. Flowers sessile --9.

8b. Flowers distinctly pedicelled --12.

9a. Sepals united below into a gamosepalous calyx --10.

9b. Sepals separate from each other --11.

10a. Calyx-lobes obtuse =Dodder, Cuscuta arvensis.=

10b. Calyx-lobes acute =Dodder, Cuscuta obtusiflora.=

11a. Flowers in dense rope-like twists on various species of herbs =Dodder, Cuscuta paradoxa.=

11b. Flowers in dense cl.u.s.ters on various species of shrubs =Dodder, Cuscuta compacta.=

12a. Tips of the petals inflexed =Dodder, Cuscuta coryli.=

12b. Tips of the petals erect or spreading --13.

13a. Capsule depressed at the summit =Dodder, Cuscuta cephalanthi.=

13b. Capsule pointed at the summit =Dodder, Cuscuta gronovii.=