143 [ 7 ] 



of which are described in the Flora of North America, but we can- 

 not yet pronounce them new. 



Tessaria borealis, DC. An aromatic shrub about three feet high 

 growing in all the deserted beds of the Gila, and in the valley of 

 the Del Norte; usually with the Fremontia, both of which are 

 abundant in those regions. 



Hymenoclea, Torr. and Gr. ined. This remarkable new genus is 

 allied to Ambrosia and Xanthium. Another species of it (H. Sal- 

 sola) was found in Fremont's second expedition, which, with the 

 characters of the genus to which it belongs, will be published in 

 another work. This species, from the scales of the involucre being 

 in a single whorl, we propose to call H. monogyra, Torr. and Gr. 

 It was found in various parts of the. valley of the Gila. 



Franseria Hookeriana, JYutt. (Yerba del Sapa.) 



Ambrosia acanthocarpa, Hooker. Very abundant from Santa 

 Fe to the 33d parallel of latitude. 



Another species of this genus, and apparently an undescribed 

 one, exists in the collection. It is suffrutescent, hoary, with the 

 leaves bipinnatifidly divided into very small obtuse segments. The 

 flowers are wanting. 



Ambrosia artemisijefolia, Linn. Bank of the Gila. 



Dicoris. Torr. and Gr. Another new genus allied to Iva of 

 which a full description and figure will hereafter be given. It was 

 found in the valley of the Gila, and in the desert of drifting sands 

 west of the Colorado. (5 to 6 inches long, and 4 to 5 wide.) 



Wyethia ovata, n. sp., TorA and Grained. Stem very stout 

 leaves orbicular, ovate, entire; somewhat coriaceous, pubescent' 

 (as are also the petioles and branches;) scales of the involucre lan- 

 ceolate; pappus. of 3 to 4 acute rigid teeth, one of which is longer 

 than the others. Abundant on the western side of the Cordilleras 

 of California. 



Silphium laciniatum, Linn. (Pilot weed.) On the Arkansas and 

 its tributaries. 



Another Silphium, with large ovate undivided leaves, was found 

 on Cariso creek. 



Engelmannia pinnatifida, Torr. and Gr.Jl. JY. Am. 2 p. 283. 

 Tributaries of the Canadian. 



Lepachys columnaris, Torr. and Gr. Rudbeckia columnaris 

 Pursh. The rays vary from being wholly yellow to entirely pur- 

 plish brown. From the head waters of the Canadian to Santa Fe\ 



Encelia farinosa, Gray ined. An aromatic shrubby plant- exud- 

 ing a yellowish resin from the branches. The leaves are 'ovate 

 softly pubescent, and hoary on both sides, with 3 to 5 prominent 

 reticulated nerves underneath. 



Helianthus petiolaris, JYutt. Upper part of the Arkansas and 

 valley of the Del Norte. 



H. lenticularis, Dougl. With the preceding. 



Coreopsis palmata, JYutt. Turkey creek. 



Simsia. A rayless, and probably new species of this genus was 

 found in the bed of the Agua Caliente, November 28th. It' is a 

 branching shrub, and -the slender bark of the irregular twigs is cov- 



