The Manual of the Botany of the Northern United States Part 45

ORDER 32. LEGUMINSae. (PULSE FAMILY.)

_Plants with papilionaceous or sometimes regular flowers, 10 (rarely 5 and sometimes many) monadelphous, diadelphous, or rarely distinct stamens, and a single simple free pistil, becoming a legume in fruit.

Seeds mostly without alb.u.men. Leaves alternate, with stipules, usually compound._ One of the sepals inferior (i.e. next the bract); one of the petals superior (i.e. next the axis of the inflorescence).--A very large order (nearly free from noxious qualities), of which the princ.i.p.al representatives in northern temperate regions belong to the first of the three suborders it comprises.

SUBORDER I. Papilionaceae. Calyx of 5 sepals, more or less united, often unequally so. Corolla inserted into the base of the calyx, of 5 irregular petals (or very rarely fewer), more or less distinctly _papilionaceous_, i.e. with the upper or odd petal (_vexillum_ or _standard_) larger than the others and enclosing them in the bud, usually turned backward or spreading; the two lateral ones (_wings_) oblique and exterior to the two lower, which last are connivent and commonly more or less coherent by their anterior edges, forming the _carina_ or _keel_, which usually encloses the stamens and pistil.

Stamens 10, very rarely 5, inserted with the corolla, monadelphous, diadelphous (mostly with 9 united into a tube which is cleft on the upper side, and the tenth or upper one separate), or occasionally distinct. Ovary 1-celled, sometimes 2-celled by an intrusion of one of the sutures, or transversely 2--many-celled by cross-division into joints; style simple; ovules amphitropous, rarely anatropous.

Cotyledons large, thick or thickish; radicle incurved.--Leaves simple or simply compound, the earliest ones in germination usually opposite, the rest alternate; leaflets almost always quite entire. Flowers perfect, solitary and axillary, or in spikes, racemes, or panicles.

I. Stamens (10) distinct.

[*] Leaves palmately 3-foliolate or simple; calyx 4--5-lobed; herbs.

(PODALYRIEae.)

1. Baptisia. Pod inflated.

2. Thermopsis. Pod flat, linear.

[*][*] Leaves pinnate; calyx-teeth short. (SOPh.o.r.eae.)

3. Cladrastis. Flowers panicled, white. Pod flat. A tree.

4. Sophora. Flowers racemose, white. Pod terete, moniliform. Herbaceous.

II. Stamens monadelphous, or diadelphous (9 and 1, rarely 5 and 5); nearly distinct in n. 14.

[*] Anthers of two forms; stamens monadelphous; leaves digitate or simple; leaflets entire. (GENISTEae.)

5. Crotalaria. Calyx 5-lobed. Pod inflated. Leaves simple.

6. Genista. Calyx 2-lipped. Pod flat. Seed estrophiolate. Leaves simple.

Shrubby.

7. Cytisus. Calyx 2-lipped. Pod flat. Seed strophiolate. Leaves 1--3-foliolate. Shrubby.

8. Lupinus. Calyx deeply 2-lipped. Pod flat. Leaves 7--11-foliolate.

[*][*] Anthers uniform (except in n. 13 and 29).

[+] Leaves digitately (rarely pinnately) 3-foliolate; leaflets denticulate or serrulate; stamens diadelphous, pods small, 1--few-seeded, often enclosed in the calyx or curved or coiled.

(TRIFOLIEae.)

9. Trifolium. Flowers capitate. Pods membranaceous, 1--6-seeded. Petals adherent to the stamen-tube.

10. Melilotus. Flowers racemed. Pod coriaceous, wrinkled, 1--2-seeded.

11. Medicago. Flowers racemed or spiked. Pods curved or coiled, 1--few-seeded.

[+][+] Leaves unequally pinnate (or digitate in n. 13); pod not jointed; not twining nor climbing (except n. 20).

[++] Flowers umbellate (solitary in ours) on axillary peduncles.

(LOTEae.)

12. Hosaekia. Leaves 1--3-foliolate. Peduncle leafy-bracteate. Pod linear.

[++][++] Flowers in spikes, racemes, or heads. (GALEGEae.)

[=] Herbage glandular-dotted; stamens mostly monadelphous; pod small, indehiscent, mostly 1-seeded; leaves pinnate (except in n. 13).

13. Psoralea. Corolla truly papilionaceous. Stamens 10, half of the anthers often smaller or less perfect. Leaves mostly palmately 3--5-foliolate.

14. Amorpha. Corolla of one petal! Stamens 10, monadelphous at base.

15. Dalea. Corolla imperfectly papilionaceous. Stamens 9 or 10; the cleft tube of filaments bearing 4 of the petals about its middle.

16. Petalostemon. Corolla scarcely at all papilionaceous. Stamens 5; the cleft tube of filaments bearing 4 of the petals on its summit.

[=][=] Herbage not glandular-dotted (except in n. 23); stamens mostly diadelphous; pod 2-valved, several-seeded; leaves pinnately several-foliolate; flowers racemose.

[a.] Wings cohering with the keel; pod flat or 4-angled; h.o.a.ry perennial herbs.

17. Tephrosia. Standard broad. Pod flat. Leaflets pinnately veined.

18. Indigofera. Calyx and standard small. Pod 4-angled. Leaflets obscurely veined.

[b.] Flowers large and showy; standard broad; wings free; woody; leaflets stipellate.

19. Robinia. Pod flat, thin, margined on one edge. Trees or shrubs.

20. Wistaria. Pod tumid, marginless. Woody twiners; leaflets obscurely stipellate.

[c.] Standard narrow, erect; pod turgid or inflated; perennial herbs.

21. Astragalus. Keel not tipped with a point or sharp appendage. Pod with one or both the sutures turned in, sometimes dividing the cell lengthwise into two.

22. Oxytropis. Keel tipped with an erect point; otherwise as Astragalus.

23. Glycyrrhiza. Flowers, etc., of Astragalus. Anther-cells confluent.

Pod p.r.i.c.kly or muricate, short, nearly indehiscent.

[+][+][+] Herbs with pinnate or pinnately 1--3-foliolate leaves; no tendrils; pod transversely 2--several-jointed, the reticulated 1-seeded joints indehiscent, or sometimes reduced to one such joint. (HEDYSAREae.)

[=] Leaves pinnate, with several leaflets, not stipellate.

24. aeschynomene. Stamens equally diadelphous (5 and 5). Calyx 2-lipped.

Pod several-jointed; joints square.

25. Coronilla. Stamens unequally diadelphous (9 and 1). Calyx 5-toothed.