28 



NATURAL HISTORY OF PLANTS. 



gascar, with bipinnate setaceous leaves possessing a glanduliferous 

 rachis and two lateral stipules. The flowers are collected into cylin- 

 drical spikes, solitary or fascicled in the axils of the leaves, or of the 

 bracts that take the place of leaves at the ends of the branches. 



Prosopis, 1 with the flower of the preceding genera, and especially 

 of Piptadenia, has indehiscent fruits like Gagnebina, but they are 

 wingless, and vary greatly in general form. The pericarp is always 

 coriaceous, with a thick, spongy or suberous mesocarp, and a carti- 

 laginous or papery endocarp, continuous with the septa between 

 the seeds, and even forming a sort of stone of variable thickness 

 round each. In the species of the section Anonychiun? the pod is 

 straight, hard, and very thick. In Adenopitf it is 

 (st^ZoZpus) cylindroidal, elongated, torulose, 4 or irregularly 

 strombuiifera. thickened or distorted. 5 The fruit of Algarobitf is 

 elongated, straight, or bowed, C3'lindrical or com- 

 pressed, narrower between the seeds, and hence mo- 

 niliform. The pod of Circinaria 1 is not only bowed, 

 but twisted more or less into a spiral ; and as its turns 

 are not all quite in one and the same plane, this fruit 

 affords a transition to Slrombocarpus* which is rolled 

 up like a corkscrew, either loosely and irregularly, or 

 very regularly (fig. 21) and with the turns of its 

 spiral in very close contact. Thus constituted, the 

 genus Prosopis contains some fifteen species 9 from all 

 tropical and subtropical regions. They are naked 

 or spiny trees or shrubs, with stipulate or exstipulate 

 leaves, whose petioles may or may not possess glands. 

 The flowers, usually axillary, form spikes, cylindrical, or more rarely 

 2'lobular or ovoidal. 



Fig. 21. 



Fruit. 



1 L., Maniiss., n. 1260.— J., Gen., 348.— 

 K., Mimos., 106.— DC, Prodr., ii. 446.— Endl., 

 Gen., n. 6821.— B. H., Gen., 591, n. 382 — 

 Olit., Fl. Trop. Afr. ii. 331. 



2 Benth., Gen., loc. cit., 2. This section in- 

 cludes two African species, with velvety ovaries 

 and internally glabrous petals. 



3 DC, Prodr., sect. 1. — Lagonychiwm Bieb., 

 Fl. Taur.-Cauc, iii. 288.— DC, Prodr., ii. 448.— 

 Deless., Ic. selec f ., \\\, 42, t. 75. — E>dl., Gen., 

 n. 6822. The petals are also glabrous internally, 

 but the ovary is glabrous as well, the branches 

 are often covered with scattered prickles. 



4 As in P. spicigera L. (Mantiss., 68,) an 

 Indian species (Bubsi., Ind., t. 25, fig. 3. — 

 Hoxb., PI. Coromand., t. 63). 



5 In a second species from Western Asia, 

 P. Slephaniana (Lagongchium Stephaniamtm, 

 Bieb., op. cit., 288 ; — Acacia Stephaniana, 

 BlEB., op. cit., ii. 449). 



c Bextii., PL llnrtweg., 13.— Tobb. & Gb., 

 in Ann. Lye. 2sew York, ii. t. 12 ; Fl. A'. Amer. 

 399.— K./ Mimos., t. 33, 34,— DC, Prodr., 

 sect. ii. — Exdl., Gen., n. 6823. 



7 B. H., Gen., loc. cit., 4. This section has 

 only a single species from tropical Africa. 



8 A. Gb.vy, PI. Lindliei/m., i. 35. — TOBB., in 

 Frem. Pep., t. 1. — Bexth., Gen., loc. cit., 5. — 

 Wali'.. .1,1,1. iv. 614. This section is made up of 

 five American species. 



9 Wali\, Rep., i. 861 ; x. 582 ; Ann., i. 259. 



