6Q PHANEROGAMIA. 



crowded lobes. The stem branches at the summit, and bears a num- 

 ber of crowded corymbs, each with a great number of flowers, on pedi- 

 cels as long as the calyx, but so aggregated as to appear capitate, as 

 well in fruit as in flower; for the axis does not at all elongate with 

 age. Petals pale yellow, spatulate, unguiculate. These, as well as 

 the rest of the floral organs, are persistent, more or less withering, 

 around the base of the pod. Siliques very short, only 2 lines long, 

 oblong, acutely four-angled, only tioice or thrice the length of tlie persistent 

 petals; the valves strongly carinate and one-nerved : the partition 

 obsolete, except at the summit, or reduced to a narrow margin. 

 Stigma depressed-capitate, subsessile. Seeds about 20 in each cell, 

 occupying two distinct series. Cotyledons incumbent. 



This is a well-marked new species of the group to which the pre- 

 ceding and S. canescens, Nutt. belong, and which would appear to be 

 fully as distinct from the true Sisymbria as is the genus Bray a. If 

 S, Sophia, S. millefolium, and S. tanaceti folium, had the seeds likewise 

 biserial, there would be no doubt of the propriety of adopting the 

 genus Descurea, Guettard, or Descurainia, "Webb & Berth. (Hugue- 

 ninia, Reichenb.) 



Plate 3, B. — Sisymbrium athrocarpum. Fig. 1. Upper part of a 

 plant. 2. The whole of a dwarf specimen : both of the natural size. 

 3, 4. Branched hairs of which the pubescence consists, magnified. 

 5. A flower, magnified. 6. A sepal. 7. A petal. 8. A flower from 

 which the sepals and petals have been removed. 9. Silique, with 

 the withering-persistent remains of the flower. 10. The replum 

 (placentae), with the vestiges of the almost obsolete partition. 11. A 

 pod transversely divided. 12. The replum, with the seeds attached. 

 13. A seed transversely divided. 14. Embryo detached entire. — All 

 the analyses more or less magnified. 



4. Sisymbrium spathul^efolium, Sp. Nov. 



S. humile; caulibus e radice perenni crassa pluribus adscendentibus 

 pilis bi—trifurcatis pubescentibm ; foliis omnibus obovato-sjmthulatis 

 carnosulis integerrimis nunc parce subdentatis glabriusculis basi 

 attenuatis subpetiolatis, summis flores infimos bracteantibus ; racemo 



