TETR ADYNAMIA. 



Orre to one foot and a half high, leafless. Whole plant dingy purplish 

 brown, pubescent. Stem swelling at the base, and very scaly 

 scales more distant upwards 5 these become bracteas among the 

 flowers, 1 at the base of each. Flowers in a long spike. Cal. of 

 two, lateral, lanceolate leaves. Cor. large. 



2. O. rubra (red Broom- Rape) , sjtem simple, cor. tubular its 

 upper lip 2-lobed lower one in 3 equal obtuse lobes, stam. 

 partially glanduloso-pilose, style glabrous. .E. B. t. 17B6 

 (bad Jig.). Hook, in Fl. Lond. New Series, .105. 



HAB. Basaltic rocks, Staffa, Messrs. Turner, Borrer and Hook. 

 Near Kirkcaldy (E. side of the hollow, near Seafieldtown, where 

 it was long mistaken for the 0. major, Mr . Arnott *) , Mi . Somerville 

 and Mr. E. I. Maitghan. Fl. July. I/ ? 



Eight to ten inches high. Whole plant a fine purplish red, piloso- 

 glandulose. Cal. of 2, entire, lanceolate leaves. I know not the 

 nature of the subsoil at Kirkcaldy, but every other station at present 

 known for this plant, in Ireland as well as Scotland, is basaltic. 



XV. TETRADYNAMIA. 



1. SILICULOSA b . 



1. CAKILE. Pouch of 2 single-seeded articulations ; upper arti- 

 culation with an erect sessile seed ; the lower one with a pen- 

 dulous seed (sometimes abortive) . Br. 



2. CRAMBE. Pouch with the upper articulation subglobose ; its 

 seed inverted, fixed to the base of the cell by its (long, curved) 

 seedstalk ; the lower articulation abortive, resembling a pe- 

 dicel. Br. 



3. CORONOPUS. Pouch 2-lobed, without valves, wingless ; cells 

 1- seeded. Cotyledons incumbent, linear. Br. 



a This gentleman informs me that I am mistaken in having given, in FL 

 Lond.y Salisbury craigs as a station for this plant. 



b No one who has at all studied the genera of plants needs be told 

 how difficult it was, nay, I may say impossible, to distinguish those of this 

 very natural family by the characters that had been given of them prior to 

 the publication of the 4th vol. of Hortus Keiuensis ; where Mr. Brown has 

 given an entirely new arrangement of the family. His genera and charac- 

 ters I have adopted : but I still fear, from the minute part of the fructifica- 

 tion (the embryo), which is here, with great propriety, brought forward, as 

 affording important distinguishing marks, that the student may shrink from 

 the task of investigation. The difficulty, however, is more in appearance 

 than in reality. The embryo being surrounded by no albumen, offers itself 

 to examination immediately upon breaking the external coat of th seed, 

 and the distinction between decumbent and incumbent cotyledons will be 

 apparent. In the former case the back of one of the cotyledons is applied to 

 the curved radicle ; in the latter the edges or margins of the cotyledons are 

 applied to it. 



