The Plants of Michigan Part 70

5b. Leaves bright-green beneath, sharply serrulate =Green Ash, Fraxinus pennsylvanica var. lanceolata.=

GENTIANACEAE, the Gentian Family

Herbs, with opposite or basal, entire, usually simple leaves and regular flowers; sepals, petals, and stamens equal in number, 4-12; ovary superior, 1-celled.

1a. Leaves reduced to small scales (1-4 dm. high; flowers small, greenish-yellow, in summer) =Bartonia, Bartonia virginica.=

1b. Leaves rounded, floating (flowers white, summer) =Floating Heart, Nymphoides lacunosum.=

1c. Leaves compound (2-4 dm. high; flowers white or bluish, early summer) =Buckbean, Menyanthes trifoliata.=

1d. Leaves simple, whorled (1-2 m. high; flowers yellowish-white, summer) =American Columbo, Frasera caroliniensis.=

1e. Leaves simple, opposite --2.

2a. Corolla rotate, with spreading lobes, 2-4 cm. broad, pink (5-8 dm.

high; summer) =Rose Pink, Sabbatia angularis.=

2b. Corolla bell-shape, each petal with a spur at the base, purplish or white, and not over 1 cm. long (1-4 dm. high; summer) =Spurred Gentian, Halenia deflexa.=

2c. Corolla bell-shape, tubular, funnel-form, or salver-form, not spurred --3.

3a. Corolla-lobes fringed (flowers bright-blue) (Fringed Gentian) --4.

3b. Corolla-lobes entire --5.

4a. Leaves lanceolate (2-8 dm. high; autumn) =Fringed Gentian, Gentiana crinita.=

4b. Leaves linear (1-4 dm. high; late summer) =Fringed Gentian, Gentiana procera.=

5a. Corolla 2 cm. long or a little less --6.

5b. Corolla 2.5-5 cm. long (late summer and autumn) (Gentian) --7.

6a. Upper leaves linear or narrowly lanceolate (2-4 dm. high; flowers pink-purple, late summer) =Centaury, Centaurium umbellatum.=

6b. Upper leaves ovate, with several princ.i.p.al veins (1-5 dm. high; flowers blue, late summer and autumn) =Gentian, Gentiana quinquefolia.=

7a. Calyx-lobes rough or ciliate at the margin (flowers blue, or rarely white) --8.

7b. Calyx-lobes smooth (2-8 dm. high) --10.

8a. Corolla-lobes spreading; leaves narrowly lanceolate, indistinctly veined (2-5 dm. high) =Gentian, Gentiana p.u.b.erula.=

8b. Corolla-lobes erect or incurved; leaves ovate to ovate-lanceolate, with 3-7 princ.i.p.al veins (3-6 dm. high) --9.

9a. Calyx-lobes equaling or exceeding the calyx-tube =Gentian, Gentiana saponaria.=

9b. Calyx-lobes shorter than the calyx-tube =Gentian, Gentiana andrewsii.=

10a. Leaves ovate or ovate-lanceolate, somewhat cordate at base (flowers greenish-white or yellowish-white) =Gentian, Gentiana flavida.=

10b. Leaves narrowly lanceolate or nearly linear, not cordate (flowers blue) =Gentian, Gentiana linearis.=

APOCYNACEAE, the Dogbane Family

Herbs, with opposite simple entire leaves and regular flowers; sepals, petals, and stamens each 5; petals united; stamens attached to the corolla; ovaries 2, with a single style or stigma.

1a. Plant creeping or trailing; flowers blue, axillary, 2-3 cm. broad (spring) =Periwinkle, Vinca minor.=

1b. Plant erect or essentially so; flowers 1 cm. broad or less (4-12 dm.

high) --2.

2a. Corolla pinkish, about 8 mm. long by 6-8 mm. broad (early summer) =Dogbane, Apocynum androsaemifolium.=

2b. Corolla white or greenish, about 6 mm. long by 4 mm. broad (summer) --3.

3a. Leaves petioled, acute at the base =Indian Hemp, Apocynum cannabinum.=

3b. Leaves sessile, rounded or truncate at the base =Indian Hemp, Apocynum cannabinum var. hypericifolium.=

ASCLEPIADACEAE, the Milkweed Family

Herbs, with simple entire leaves and regular flowers; juice usually milky; except in the first species, which is a twining vine. The flowers have an unusual structure: calyx of 5 sepals; petals 5, united with each other, and spreading or reflexed so that they conceal the calyx; stamens 5, united with each other and with the stigma to form a complex organ in the center of the flower; ovaries 2; on the back of each stamen is a colored projecting hood, which is frequently the most conspicuous part of the flower, and may be mistaken for the corolla.

1a. Twining vine, with dark purple flowers (summer) =Black Swallow-wort, Cynanchum nigrum.=

1b. Stems not twining --2.

2a. Leaves whorled (3-6 dm. high; summer) (Milkweed) --3.

2b. Leaves opposite or alternate --4.

3a. Leaves in whorls of 4, lanceolate (flowers pink) =Milkweed, Asclepias quadrifolia.=

3b. Leaves in whorls of 4-7, linear (flowers greenish-white) =Milkweed, Asclepias verticillata.=