SIMARUBACEAE, the Quassia Family
Trees, with pinnately compound leaves and small greenish-yellow flowers in large panicles in early summer, ripening into winged fruits.
| One species in Michigan, escaped from cultivation chiefly in towns | Tree of Heaven, Ailanthus glandulosa. |
POLYGALACEAE, the Milkwort Family
Small herbs, with alternate or whorled simple leaves, and small irregular flowers; sepals 5, petals 3, stamens 6 or 8, more or less united with each other and with the petals.
| 1a. All of the leaves alternate [— 2.] | |
| 1b. Some or all of the leaves in whorls (1-4 dm. high; flowers greenish, purple, or white; summer) (Milkwort) [— 6.] | |
| 2a. Flowers few, loosely clustered, 15-20 mm. long (1-3 dm. high; flowers purple; early summer) | Flowering Wintergreen, Polygala paucifolia. |
| 2b. Flowers numerous, in a spike or raceme [— 3.] | |
| 3a. Stem-leaves minute, linear-subulate; stem slender, erect, 3-7 dm. high (flowers pink; summer) | Milkwort, Polygala incarnata. |
| 3b. Stem-leaves narrowly oblong or broader; stem generally 1-4 dm. high [— 4.] | |
| 4a. Flowers in a short thick obtuse very dense spike (flowers greenish or purple; summer) | Milkwort, Polygala sanguinea. |
| 4b. Flowers in a slender tapering spike [— 5.] | |
| 4c. Flowers in a raceme; plants with subterranean flowers also (flowers purple; early summer) | Milkwort, Polygala polygama. |
| 5a. Leaves linear or nearly so (flowers purple; summer) — 7b. | |
| 5b. Leaves lanceolate or oblong-lanceolate, 2-6 cm. long (flowers white; late spring) | Seneca Snakeroot, Polygala senega. |
| 5c. Leaves ovate to ovate-lanceolate (flowers white; late spring) | Seneca Snakeroot, Polygala senega var. latifolia. |
| 6a. Spike oval, thick, obtuse | Milkwort, Polygala cruciata. |
| 6b. Spike acute [— 7.] | |
| 7a. Spike densely flowered, 1-2 cm. long | Milkwort, Polygala verticillata. |
| 7b. Spike loosely flowered, 2-5 cm. long | Milkwort, Polygala verticillata var. ambigua. |
EUPHORBIACEAE, the Spurge Family
Herbs, with alternate, opposite, or whorled leaves and usually milky juice. Flowers small or minute and inconspicuous, without petals and frequently without calyx. In our commoner species, several staminate flowers, each consisting of a single stamen only, and one pistillate flower, consisting of a single pedicelled 3-lobed ovary only, are included within a 4-5-lobed involucre, which is sometimes colored and resembles a calyx or corolla.
| 1a. Stem-leaves alternate; inflorescence axillary; flowers with calyx and several stamens (3-8 dm. tall; flowers greenish or purplish; summer) (Three-seeded Mercury) [— 2.] | |
| 1b. Stem-leaves opposite, usually inequilateral at base; flowers as described for the family; apparent flowers in axillary clusters (summer and autumn) (Spurge) [— 3.] | |
| 1c. Stem-leaves alternate; inflorescence a terminal umbel-like cluster, with its branches subtended by opposite or whorled leaves; flowers as described for the family (Spurge) [— 9.] | |
| 2a. Leaves ovate or ovate-lanceolate; flower-clusters shorter than the subtending bract | Three-seeded Mercury, Acalypha virginica. |
| 2b. Leaves lanceolate to oblong; flower-clusters equaling or exceeding the subtending bract | Three-seeded Mercury, Acalypha gracilens. |
| 3a. Stem and foliage glabrous [— 4.] | |
| 3b. Stem and foliage more or less pubescent (stems prostrate or ascending, 1-4 dm. long) [— 7.] | |
| 4a. Erect or ascending, usually without basal branches (2-4 dm. tall) | Spurge, Euphorbia preslii. |
| 4b. Prostrate or spreading, branched from the base (stems 1-4 dm. long) [— 5.] | |
| 5a. Leaves entire; plants of the shores of the Great Lakes | Spurge, Euphorbia polygonifolia. |
| 5b. Leaves serrulate [— 6.] | |
| 6a. Leaves broadly oblong or obovate; seeds obscurely wrinkled | Spurge, Euphorbia serpyllifolia. |
| 6b. Leaves narrowly oblong; seeds with prominent transverse ridges | Spurge, Euphorbia glyptosperma. |
| 7a. Seeds black | Spurge, Euphorbia hirsuta. |
| 7b. Seeds red [— 8.] | |
| 8a. Leaves oblong | Spurge, Euphorbia maculata. |
| 8b. Leaves elliptical to obovate; involucre split down one side | Spurge, Euphorbia humistrata. |
| 9a. Flowers subtended by conspicuous petal-like white appendages (part of the involucre) (4-10 dm. tall; summer) | Spurge, Euphorbia corollata. |
| 9b. Flowers not subtended by petal-like appendages [— 10.] | |
| 10a. Stem-leaves below the inflorescence serrulate (2-5 dm. high; summer) [— 11.] | |
| 10b. Stem-leaves below the inflorescence entire [— 13.] | |
| 11a. Upper leaves acute | Spurge, Euphorbia platyphylla. |
| 11b. Upper leaves obtuse, rounded, or notched at the apex [— 12.] | |
| 12a. Leaves of the involucre broadly triangular-ovate, widest near the base | Spurge, Euphorbia obtusata. |
| 12b. Leaves of the involucre broadly obovate to nearly circular, widest near or above the middle | Spurge, Euphorbia helioscopia. |
| 13a. Stem-leaves narrowly linear, less than 3 mm. wide (2-4 dm. high; late spring and summer) | Cypress Spurge, Euphorbia cyparissias. |
| 13b. Stem-leaves narrowly oblong-spatulate, more than 5 mm. wide, and more than 3 times as long as wide (2-6 dm. high; summer) [— 14.] | |
| 13c. Stem-leaves obovate to nearly circular, not more than twice as long as wide (1-4 dm. high) [— 15.] | |
| 14a. Leaves at base of umbel narrow, resembling those on the stem | Spurge, Euphorbia esula. |
| 14b. Leaves at base of umbel broad, resembling those of the inflorescence | Spurge, Euphorbia lucida. |
| 15a. Upper stem-leaves distinctly narrowed at the base; introduced species of waste places (summer) | Spurge, Euphorbia peplus. |
| 15b. Upper stem-leaves rounded at the sessile base; native species of woodlands (spring and early summer) | Spurge, Euphorbia commutata. |