MIMOSACEAE. 155 



Valves of the pod not separating from the continuous margin. 

 Valves of the pod thick, coiling in dehiscence in 



our species. 1. Pitheoolobium. 



Valves 01! the pod flat and papery. 2. AlUzzia. 



Valves of the pod separating from the continuous 



margins. 3. Lysiloma. 



Pods elastically dehiscent from the base. 4. Anneslia. 



Stamens distinct. 



Seeds in one row ; ovary stipitate. 5. Acacia. 



Seeds in two rows^ ovary sessile. 6. VacheUia. 



B. Stamens only as many or twice as many as the corolla- 

 segments. 

 Anthers without glands. 



Valves of the pod separating from the continuous margin. 7. Mimosa. 

 Valves of the pod not separating from the margins. 



Shrubs or trees ; seeds transverse. 8. Leucaena. 



Herbs ; seeds longitudinal or oblique. 9. Acuan. 



Anthers tipped by glands (at least in the bud). 



Herbs ; flowers capitate ; pods flat. 10. Neptunia. 



Trees; flowers spicate; pods nearly terete. 11. Prosopis. 



1. PITHECOLOBIUM Mart. Hort. Monac. 188. 1829. 



Shrubs or trees, often spiny, with 2-pinnate leaves, and small, mostly per 

 feet flowers in heads or spikes. Calyx 5-6-toothed. Corolla 5-6-lobed. Sta- 

 mens many, long-exserted, the filaments partly united into a tube, the anthera 

 small. Ovary several-many-ovuled ; style slender; stigma small, capitate. 

 Pods flattened, mostly contorted or curved, 2-valved. Seeds mostly arillate. 

 [Greek, referring to the contorted pods of the typical species.] Perhaps 100 

 species, widely distributed in tropical and subtropical regions. Type species: 

 Mimosa Unguis-cati L. The original spelling of the genus is Pithecellobium. 



Pinnae with 1 or 2 pairs of leaflets. 

 Leaflets 1-6 cm. long or longer. 



Leaflets chartaceous ; petioles of at least the lower leaves longer than the 



petiolules. 1. 2'. Unguis-cati. 



Leaflets coriaceous ; petioles shorter than the petiolules 



or as long. 

 Petioles and petiolules stout, thick, the petiolules 



often 2-3 cm. long ; leaflets large, 2.5-7 cm. long. 2. P. guadalupense. 

 Petioles and petiolules slender, 2-5 mm. long ; leaf- 

 lets 1-3 cm. long. 

 Leaflets strongly spinulose-mucronate ; shrub or 



small tree with erect branches. 3. P. mucronatum. 



Leaflets rounded, or merely mucronulate ; low 



shrubs with divergent branches. 4. P. bahamense. 



Leaflets 2-8 mm. long; petioles 6 mm. long or less. 5. P. Hystrix. 



Pinnae with 3-6 pairs of leaflets. 6. P. discolor. 



1. Pithecolobium Unguis-cati (L.) Mart. Hort. Monac. 188. 1829. 



Mimosa Unguis-cati L. Sp. PI. 517. 1753. 



Pithecolobium flavovirens Britton, Bull. N. Y. Bot. Gard. 3: 442. 1905. 



A shrub up to 6 m. high, rarely a small tree 8 m. high, usually armed with 

 stipular spines 2 cm. long or less, the foliage glabrous. Petiole 5-20 mm. long, 

 bearing a round gland at the summit; pinnae 2, each with one pair of obliquely 

 obovate or oblong, obtuse, thin leaflets, 1-5 cm. long; heads slender-peduncled, 

 in terminal racemes; flowers sessile; calyx about 2 mm. long; corolla 5-6 mm. 

 long; stamens 10-15 mm. long, yellowish or pinkish; pod coiled or curved, red, 

 compressed, somewhat constricted between the seeds, 5-10 cm. long, about 7 

 mm. wide; seeds nearly black, shining, 4-6 mm. broad. 



Scrub-lands, Watling's Island, Acklin's Island, Mariguana, Grand Turk and 

 Inagua : Florida ; West Indies ; Yucatan ; northern South America. CAT'S-CLAW. 



The characters thought to differentiate P. flavovirens specifically do not seem 

 constant, since specimens from other islands obtained during subsequent explora- 

 tion appear to connect them with those of P. Unguis-cati. 



