313 [ 174 ] 



the ovary. Silicle didymous : the carpels obovoid-globose, one-seeded, 

 (or rarely two-seeded,) indehiscent, separating from the base of the persis- 

 tent subulate spinescent style : pericarp crustaceo-coriaceous. Seed ovate, 

 somewhat compressed ; testa membranaceous, the lining much thickened 

 and fleshy. Cotyledons incumbent, linear-oblong ; radicle opposite the 

 placentae. — A smooth annual herb. Leaves temately parted, on long 

 petioles ; the leaflets ovate or oblong, entire petiolulate. Flowers in nu- 

 merous axillary crowded short capitate racemes, small and yellow. 



Oxystylis lutea. Torr. and Frem. 



On the Margoza river, at the foot of a sandy hill ; only seen in one place, 

 but abundant there. The specimens were collected on the 2Sth of April, 

 and were in both flower and fruit. 



A rather stout plant ; the stem erect, a foot or 15 inches high, simple or 

 a little branching below, leafy. Leaflets 1 — li inch long, obtuse. Heads 

 of flowers about half an inch in diameter, not elongating in fruit. Calyx 

 shorter than the corolla ; the sepals acute, yellowish, tipped with orange. 

 Petals about two lines long. Fruit consisting of two roundish indehiscent 

 carpels, which at maturity separate by a small base, leaving the indurated 

 pointed style. The epicarp is thin, membranaceous,and slightly corrugated. 



This remarkable plant seems to connect Cruciferae with Capparidaeeae. 

 The clusters of old flower stalks, with their numerous crowded spinescent 

 styles, present a singular appearance. 



Thamnosma. Torr. and Frem. — n. gen. 



Flowers hermaphrodite, (or polygamous?) Calyx 4-cleft. Corolla 4- 

 petalled, much longer than the calyx ; the aestivation valvate. Stamens S, 

 in a double series, all fertile. Ovaries 2, sessile and connate at the summit 

 of a stipe, each with 5 or 6 ovules in 2 series ; styles united into one ; 

 stigma capitate. Capsules 2, sessile at the summit of the stipe, subglobose, 

 united below, (one of them sometimes abortive,) coriaceous, 1 — 3-seeded. 

 Seeds curved, with a short beak, black and minutely wrinkled ; the radicle 

 inferior. Embryo curved ; cotyledons broadly linear, incumbent. 



Thamnosma Montana. Torr. and Frem. 



A shrub of the height of one or two feet, branching from the base, with 

 simple, very small linear wedge-shaped leaves. The flowers are apparently 

 dark purple, in loose terminal clusters. The whole plant has a strong aro- 

 matic odor, and every part of it is covered with little glandular dots. Al- 

 though nearly allied to Xanthoxylum, we regard it as a peculiar genus. It 

 grows in the passes of the mountains, and on the Virgen river in Northern 

 California. The greater part of it was already in fruit in the month of May. 



Prosopis odorata. Torr. and Frem. 



Branches and leaves smooth ; spines stout, mostly in pairs, straight ; pin- 

 nae a single pair ; leaflets 6 — S pairs, oblong-linear, slightly falcate, some- 

 what coriaceous, rather obtuse ; spikes elongated, on short peduncles ; co- 

 rolla three times as long as the calyx ; stamens exserted ; legume spirally 

 twisted into a compact cylinder. 



A tree about 20 feet high, with a very broad full head, and the lower 

 branches declining to the ground ; the thorns sometimes more than an inch 



