led us I" 



)lislHMl I'V 



'iliiiiijili'i'i" 



i.'fiins, iiiv 



fiiniis all 

 leaves iiii'l 

 •m-atli tl <• 

 (1, (K'j)i'i'l- 

 is stroiiiiiy 



of pinuitc 

 •h terms is 



COl'LTKR AXI) K<»SK — NoUTII AMKKKAN IMMKLMFKUA K. IHl 



|iiiiiia<'," "stviiu'iit."*," " ulliinatc ilivisitiiiH," etc., arc purely arbitrary ami ilitlicuU 



I application. 



riicre is irrcat variation in tjie devclopiiiciit of ilorsal ami interineiliatc winjrs. Thc> 



• terals arc always present, ami lia\c the charactcristie thick ami corlvv structure, 

 'ill the ilcirHal ami intermediate ribs may all he winu'cii, or only sonic of thcni inuy 

 l>e wint-'cil, or tlu-y may licar no wIul's at all, ami these variations may occur even in 

 ilie same plant. 



The presence of an invoimie is also often a matter of uncertainty. In the usual 

 ■ use there is no involucre in the i:enus, hut in some of the s|H'cieH a vestip- in the 

 !• rm of a low sheath is apparent. Occasionally this sheath heconies toothed, an<l in 

 ( /■((«//((•/ and <'. iinrhrrriii the teeth ai'»' ."Joinetimes jiroduccd into narrow hracts. 



Two very natural sections of the >,'enus are «'vident; the one w ith a conipa<'t head- 

 hkc umlicl and white llowcrs. the other with an open undtel and yellow flowers. 



In the more technical cliaracteis ' '. i/lnlinxii.i is tin' most exceptional sjiecies, with 

 ii> SI lilary oil mhes ami small in\iihicellate hractlot.x^ hut in its combination of 

 I liaraciers it can not be separated from the other spoeioH. 



I iiibcis i.'lobose; llowcrs white; involucre wanting;. 

 ( >il tidies several in the intervals. 

 I'ruit j;lal irons. 

 luMilucels of linear entire liratlets; fruit orbicular, not e.\ceed'ng 8 mm. in 

 diaini'ter. 

 I^eaf se<j;inents small and narrow; fruit <> to s mm. in diameter. I. ('. iicniilin. 



Leaf sei,r|iieiits shorter and more obtuse; fruit larpT L'. < '. /iiirriii. 



Iiuoliicels of liroail more or less cleft bi'actlets; fruit broaiily oblong. It) mm. 



louir •>. ' '. Ii'ihfrfjil. 



i'liiil pn belli lent at apex 1. <'. iiiii/iiiY))litilii.i. 



oil tubes solitary in l he intervals 5. (\ i/li)lt<»in.i. 



I iiibels open; llowcrs yellow ; a vcsfi^'of an involucre and sometimes bracts. 



Leaf se!.'nieiiis narrow (>. ('. ffinilen. 



Leaf scirnicnts broad 7. C. iiewbcrviji. 



\. Cymopterus acaulis (Pufsli) HydluM-o-. Hot. Sufv. Neh. 3; 38. 1804. 



Srilinnii >i,'aiil, I'lirsh, Fl. 2: 7;!2. 1H14. 



Tlm/i.-'iii i/lonii mill Null. (icn. 1: 1S4. ISIS. 



<)iniuiili riiy iiliiiiii riilii^ \H'. i'rodr. 4: •_'(M. ISoO. 



I 'iliiii>i>liri"< iiiiiijii stria Tiirv. \ <iray, I'M. 1: <)24. 1S40. 



Low (7 to L't> (Ml.) tiiid oliil (foils, with ii .short e!iiicl«>.\ hoiirinj; a clus- 

 tcf (if h'iivcs iLiid peduncles; leaves iiiei'iniuo" from j)iiiiuite to l)ii)iiiniitc; 

 iiltiiiiiite seoincnls mostly small and narrow: peduncles mostly shorter 

 than the leaves; rays and pedicels vei'y short, makino- a rather com- 

 pact cluster; iiivolucel of liiiciir and entire more or less united foliose 

 I'lactlels; Mowers white; fruit tJ to !S mm. in diameter, with 'A to 5 

 I'load winos on each carpel; oil tubes small, 4 to S in the intervals (or 

 (loiihle the numtxM' where a ril) has heen suppressed), 8 to 14 ou the 

 cDinmi.ssunil si(l(>. 



Type locality, •'in upper Louisiana;" collected by Bmdhiry,' type 

 ^liecimen said by l*iii'sh to l)e in Herb. Bi'adbury. 



Dry i)lains from Arkiuisas to C'olonido on the south, and extending 

 northward into the oreat plains of Canada. 

 5872 13 



