146 PROCEEDINGS OF THE AMERICAN ACADEMY 



Vix genuinum, 3-4-phyllum, nempe flores in capitulum digest! brac- 

 teis dilatatis fulcrati, quarum 3-4 extima? vacua? involucrum 



referentes 1. Nemacaulis. 



Genuinum, gamophyllum (perigonium saepissime corollinum), 

 Multi-pauciflorum, pedicellis exsertis cum flore articulatis basi 

 tenuiter bracteolatis. 

 Dentibus lobisve muticis : achenium triquetrum. . 2. Eriogonum. 



Lobis (4) aristatis, tubo nudo : acbenium lenticulare. 3. Oxytheca. 



Uni - triflorum, juxta basim 3 - 6-calcaratum. . . 4. Centrostegia. 

 Uniflorum, inappendiculatum, flore subincluso pedicello srepius 



brevi nunc subnullo articulato 5. Chorizanthe. 



Plane nullum : perigonium subcoriaceum involucrum Chorizanthes 



simulans, stamina ad faucem gerens. ... 6. Lastarri^a. 

 2. Involucrum monophyllum bracteasfornie, nempe e bractea tenui florem 

 solitariumam plectente, fructifero reticulata dorso bigibberoso- 

 saccato. Folia nunc lobata vel dentata. 



Tribus II. PTEROSTEGIE^, & 7. Pterostegia. 



1. NEMACAULIS, Nutt. 



Flores Eriogoni, sed breviter pedicellati, in capitulum digesti, singuli 

 bractea suffulti. Bractea? herbaceaa, extus glaberrima?, intus lana longa 

 implexa alba vestitse, exteriores 3-4 vacua? rotundata?, involucrum 

 referentes, sequentes paullo longiores et gradatim decrescentes stipitata?. 

 Stamina 3. — Herba annua, foliis radicalibus vel subradicalibus spathu- 

 latis utrinque mollissime albo-lanatis, scapis filiformibus parce divari- 

 cato-dichotomis, capitulis parvis alaribus et secus ramos dissitis arete 

 sessilibus. 



1. N. Nuttallii, Benth. in DC. Prodr. 14, p. 23. N. denudata 

 S? W. foliosa, Nutt. PI. Gamb. (Jour. Acad. Philad. n. ser. 1) p. 168. 

 Sandy beach near San Diego, California, Nuttall, Cooper. Perigonium 

 whitish-yellow, glabrous. This rare plant has much the habit of an 

 Eriogonum of the Virgata Annua group, but the bracts are only to be 

 compared with those of E. angulosum. 



2. ERIOGONUM, Michx. 



Involucrum multiflorum rariusve pauciflorum, rarissime uniflorum, 

 campanulatum, turbinatum, vel cylindraceum, plerumque 5 - 8-denta- 

 tum seu lobatum, muticum. Flores cum pedicellis suis per anthesin ex 

 involucro pi. m. exsertis articulati : bracteolre saepius tenerrimi vel an- 

 gustissima?. Perigonium 6-partitum seu profunde 6-fidum. Stamina 9. 

 Achenium triquetrum, in paucis trialatum. — Herba? vel suffrutices 

 American Borealis pra3cipue Occidentalis, paucas ad terras adjacentes 

 Mexicanas. 



