MIMOSACEAE 581 



apiculate or slightly acuminate, strongly nerved beneath : peduncles armed with slender 

 prickles : pods 3-15 cm. long, beaked^ densely prickly or sometimas sparingly so. 



In dry soil, Virginia to Florida and South Dakota to Arkansas, Texas and the Gulf of Mexico. 

 Spring and summer. 



2. Morongia angustata (T. & G. ) Britton. Stems sparingly armed with recurved 

 prickles, the angles not conspicuously paler than the rest of the stem, 3-15 dm. long, 

 simple or sparingly branched : leaves with 6-16 pinnae ; leaflets many, the blades 

 narrowly oblong, 1.5-7 mm. long, scarcely or not at all nerved ; peduncles armed like the 

 stem : pods 5-15 cm. long, beaked, densely or sparingly prickly. 



In dry soil, Virginia to Tennessee, Texas and Florida. Spring and summer. 



3. Morongia Iktideas Small. Stems usually bright green, 3-10 dm. long, with 

 conspicuously pale and sharp angles and still paler prickles : leaves with 4 pinnae or rarely 

 some of them with only 2 jnnnae ; leaflets many, the blades thick, oblong, 3-8 mm._ long, 

 apiculate, not nerved : j^ed uncles much stouter than the petioles, with few pale prickles : 

 pods stout, 3-7 cm. long, the sides with broad prickles, the broad margins scarcely or only 

 slightly armed ; beak 1-1.5 cm. long. 



In dry soil, Kenedy, Carnes County, Texas. Spring and summer. 



4. Morongia Roemerikna (Scheele) Heller. Stems armed with very small prickles, 

 3-12 dm. long, prominently but not conspicuously angled : leaves with 4-8 pinnae ; 

 leaflets many, the blades olalong, 4-5.5 mm. long, apiculate, not nerved, more or less 

 ciliate : peduncles much stouter than the petioles, and armed like them, and with nurner- 

 ous smaller bristles crowded near the apex: pods flattened, 3.5-4.5 cm. long, the sides 

 with very fine prickles, the margins with stouter prickles ; beak 4-5 mm. long. 



In stony soil, southern Texas. Spring. 



11. MIMOSA L. 



Shrubby plants or trees, or rarely herbs, usually thorny or prickly. Leaves often 

 sensitive, with 2-pinnate blades : leaflets four or numerous. Flowers perfect or polygamous, 

 in axillary, white or colored head-like or cylindric spikes. Calyx mostly 4-5-lobed, some- 

 times obsolete. Corolla of usually 4-5 well united petals. Stamens 4-10, exserted : fila- 

 ments distinct. Ovary sessile or nearly so. Ovules 2-several. Pods flat, sometimes 

 conspicuously jointed, often prickle-armed, the valves separating from the persistent 

 margins. 



Stamens as many as the corolla-lobes. 1. M. pudica. 



Stamens twice as many as the corolla-lobes. 

 Shrubs or trees with hard wood. 



Branchlets and petioles or their divisions glabrous. 



Leaves usually with 2 pinnaei; leaflets 6-10, the blades oval or orbicular- 

 oval, 2-4 mm. long : pods armed. 2. M. borealis. 

 Leaves usually with 4-6 pinnae ; leaflets usually 12, the blades oblong or 



oblong-obovate, 4-6 mm. long: pods unarmed or nearly so. 3. M.fragrans. 



Branches and petioles or their divisions puberulent or pubescent. 



Leaves with 2-1 or rarely 6 pinnae ; leaflets 4-12. 4. 3f. Texana. 



Leaves with 6-many pinnae ; leaflets numerous. 5. M. Lindheimeri. 



Herbs or undershrubs or soft-woody climbing shrubs. 



Climbing : foliage tomentose or puberulent : leaflets with blades less than 



twice as long as broad. 6. M. malacophylla. 



Prostrate and creeping or erect : foliage strigose or strigillose : leaflets with 

 blades over twice as long as broad. 

 Erect or ascending : peduncles becoming 1-2 cm. long : pods 8-15-seeded. 7. M. Berlandien. 

 Prostrate : peduncles becoming 5-20 cm. long : pods 2-4-seeded. 8. M. strigillosa. 



1. Mimosa pudica L. Herbaceous or somewhat shrubby, several dm. tall, the stems 

 usually branched, more or less hirsute with downy hairs. Leaves with 1 or 2 approximate 

 pairs of pinnae : peduncles 1-4 cm. long : pods often densely clustered, 1-2 cm. long, the 

 valves glabrous, the margins armed with spreading bristles. 



In waste places, about the cities of the Gulf States. Naturalized from tropical America. 



2. Mimosa borealis A. Gray. A glabrous armed shrub usually over 1 m. tall, with 

 the spines beside the axils. Leaves inconspicuous, usually with 2 pinnae ; leaflets 6-10, 

 the blades oval, or orbicular-oval, 2-4 mm. long, thick, glaucescent : peduncles slender, 

 12-18 mm. long : pods 2.5-5 cm. long, usually armed on one or both margins, deeply con- 

 stricted, the segments often 4. 



In dry soil, the Indian Territory and Texas. 



3. Mimosa fr^grans A. Gray. A glabrous armed shrub, usually less than 1 m. tall, 

 with the spines beside the axils. Stems much branched : leaves mostly with 2-6 pinnae; 

 leaflets 10-16, the blades oblong to oblong-obovate, 4-6 mm. long, usually obtuse, promt- 



