CRUCIFER.E. 129 



Conspectus of the Genera of the United States. 



Ser. I. SiLiquosiE. — Silique 2-valved, jointless. (Cotyle- 

 dons plane, in N. Amer. species.) 



Tribe I. ARABIDE^E. — Cotyledons plane, parallel with the parti- 

 tion, accumbent (o=), one edge lying against the ascending radicle, which 

 occupies the side remote from the placenta. (Embryo straight in Leaven- 

 worthia.) Silique elongated or sometimes short, many-seeded. 



* Silique terete or slightly compressed ; the valves nerveless or nearly so. 

 Nasturtium. (Plate 53.) Silique short, often a silicle. Seeds numer- 

 ous, two-ranked in each cell, very small, punctate, on capillary fu- 

 niculi. Calyx spreading : petals sometimes wanting. 



Iodanthus. (Plate 54.) Silique linear. Seeds one-ranked in each cell, 

 marginless, as broad as the septum. Calyx erect. 



* * Silique compressed ; the valves flat and nerveless. (Seeds 1-ranked.) 

 Cardamine. (Plate 55.) Silique linear or linear-lanceolate. Seeds 



wingless, on filiform funiculi. 

 Dentaria. (Plate 56.) Silique lanceolate. Seeds wingless, on dilated 



and flattened funiculi. 

 Leavenworthia. (Plate 57.) Silique oblong. Seeds winged. Em- 

 bryo straight ! 

 * * * Silique compressed, or somewhat quadrangular; the valves 1-nerved. 

 Arabis. (Plate 58.) Silique linear, elongated ; the valves nearly flat, 



1-nerved. Seeds 1-ranked in each cell. Petals somewhat unguicu- 



late or sessile, the claw plane. 

 Turritis. (Plate 59.) Silique, &c, as in Arabis. Seeds 2-ranked in 



each cell. 

 Streptanthus. (Plates 60, 61.) Silique linear, elongated ; the valves 



flat or flattish, 1-nerved. Seeds 1-ranked in each cell. Claw of the 



petals canaliculate or involute, commonly twisted. 

 Barbarea. (Plate 62.) Silique linear, nearly quadrangular from the 



carinate- 1-nerved valves. Seeds 1-ranked. Flowers yellow. 



Tribe IT. SISYMBRIE^E. — Cotyledons plane, placed with their 

 edges to the partition, incumbent (o||), the back of one of them lying against 

 the ascending radicle, which occupies the side remote from the placenta, 

 sometimes oblique, so as to become partly accumbent. Silique mostly linear 

 and elongated, many-seeded. 



# Silique not stipitate. 

 Erysimum. (Plate 63.) Silique linear, quadrangular, the valves acute- 

 ly carinate- 1-nerved. Calyx erect. 

 Sisymbrium. (Plate 64.) Silique linear or oblong, terete or 4 - 6-an- 

 gular ; the valves convex, 1-3-nerved. Calyx equal, usually open. 

 » # Silique long-stipitate, linear. Petals with long claws. 



