486 PATAGONIAN EXPEDITIONS I BOTANY. 



perigynous, flowers, with the odd sepal anterior; and monocarpellary 

 ovary, becoming a legume. Endosperm usually none ; cotyledons large, 

 fleshy. 



Species exceeding 7,000, many cosmopolitan. Some species are 

 characteristic of particular regions ; especially of Australia, which 'is head- 

 quarters of the family. 



The following subfamilies are sometimes regarded as distinct families. 



I. MIMOSE/E : p. 488. 



Leaves bi-tri-pinnate or reduced to phyllodes. Flowers regular ; the 

 calyx-lobes and petals valvate. Stamens isomerous with the perianth- 

 divisions, or commonly numerous. 



II. CESALPINIE^E : p. 491. 



Leaves simple, or simply- or bi-pinnate. Flowers more or less irregu- 

 lar; the posterior petal enclosed by the lateral petals. Stamens 10, or 

 fewer, distinct or united. 



III. PAPILIONACE/E : p. 495. 



Leaves simply compound, rarely simple. Flowers papilionaceous ; the 

 posterior petal enclosing the lateral petals. Stamens 10, mon- or diadel- 

 phous or distinct ; rarely 9 or 5. 



KEY TO THE GENERA. 

 A. Flowers regular. Petals and sepals valvate. Stamens as many, or twice as many as the petals. 



Trees or shrubs with bipinnate leaves, sometimes reduced. (MIMOSE^:.) 

 b. Anthers glandless. Pod flat, its valves at length separating from the persisting sutures. 



I. Mimosa, p. 488. 



bz. Anthers with a deciduous gland. Pod convex, straight or twisted. Seeds with endo- 

 sperm. Petals united. 2. Prosopis, p. 489. 

 AA. Flowers zygomorphic ; the petals imbricate. 



B. Flowers not papilionaceous ; posterior petal internal. Calyx-segments almost or quite 



separate. (C^SALPINE^:.) 

 c. Leaves even-pinnate. Stamens 10 or 5. Anthers basifixed, opening terminally. 



3. Cassia, p. 491. 

 c2. Leaves bipinnate. Stamens 10, subequal. Anthers opening laterally. Ovary free. 



Flowers racemose or panicled. 

 d. Calyx-lobes valvate in the bud. Pod sessile, many-seeded. Leaflets in many 



pairs. Unarmed trees with handsome flowers. 4. Poinciana, p. 492. 



d2. Calyx-lobes long and subequal, nearly valvate. Pod sessile, flat, 2-many-seeded. 



Low, gland-punctate herbs or undershrubs. 5. Hoffmanseggia, p. 493. 



</3_ Calyx-lobes imbricate in the bud. 



e. Pod i -seeded, with long bristles, slightly stalked. Viscous shrub. 



6. Zuccagiiia, p. 494. 



