OF ARTS AND SCIENCES. 189 



Hemizonella. Hemizonia § Hemizonella Gray, Proc. Am. Acad. 

 6, p. 548. Upon a review of the group, it seems proper that these little 

 plants should constitute a genus. They differ from Hemizonm not 

 only in the reduction of the disk-flowers to unity, but in the complete 

 enclosure of the achenia in the involucral scale, after the manner of 

 Madia, yet with a difference which answers to the different form of 

 the achenium itself: their leaves also are mainly opposite, in which 

 they are unlike both Harpcecarpus and Hemizonia. The species are 

 as follows : — 



Hemizonella minima. Hemizonia (^Hemizonella) minima Gray, 

 Proc. Am. Acad. 6, p. 548. 



Hemizonella parvula. Hemizonia parvula Gray, 1. c. 



Hemizonella Durandi. Hemizonia Durandi Gray, 1. c. 



Hemizonia DC. The only change by the Genera Plantarum is the 

 incorporation of Calycadenia, which had become inevitable or nearly 

 so. Some of the external disk-flowers not rarely perfect their achenia. 

 To most of the species of Hemizonia the character " achenia loevia " 

 is inapplicable. When the genus was worked up for the Flora of 

 North America, several species were not well understood. All are 

 annuals, or at most biennials. The subjoined summary of the arrange- 

 ment adopted for the forthcoming Flora of California may be use- 



mon Tanvaedoi the eastern part of California ; var. eacemosa, Madorella racemosa 

 Nutt., the achenia of which are with or without nerve-angled sides; and var. 

 DissiTiFLORA, MadoreUa disshijlora Nutt., a depauperate or slender form, with 

 fewer-flowered heads and shorter and broader achenia. 



6. M. GLOMERATA Hook. Fi. Bor.-Am. Amida gracdis and A. hirsiita Nutt., 

 forming one and a very distinct species of true Madia, having ray-flowers 

 reduced to four, three, or even to one or none at all, the disk-flowers also very 

 few. The akenes are straightish and somewhat fusiform, sometimes flattened 

 and merely nerved, but at maturity those of the disk almost prismatic, having 

 4 or 5 acute angles. With no. 285 of Hall's Oregon collection some M. sativa 

 was mixed in the distribution. 



§ 3. Harp^carpus. {Harpcecarpus Nutt.) Ligulae brevissimte 4-8 : flos disci 

 unicus intra cupulam 3-5-dentatam, fertilis : corolla3 glabra : achenia radii 

 obovato-lunata, apiculata, disci rectum oblique obovatum. Capitula pusilla, 

 pedunculo filiformi, involucri squamis apice vix appendiculatis. 



SI. FiLiPES Gray, Proc. Am. Acad. 8, p. 391. Sclerocarpus exiguus Smith? 

 Harpaicarpus madarioides Nutt. ; Torr. & Gray, 1. c. H. exiguus Gray, in Bot. 

 Mex. Bound, p. lOl! On a wider comparison of specimens, I conclude that we 

 have only one species of this group. The size of the achenia and the prominence 

 of their beak-like apiculation are variable. 



