FLORA OF THE DISTRICT OF COLUMBIA. 



293 



50. CENTAUREA L. 



Besides the species entered below, each of the following, all natives of Europe, hajn 

 been collected once in our region: Cmtaurea solstitialis L., Vienna, July, 1909 (C L. 

 Shear); C. vochinensis Bernh., along the Pennsylvania Railroad, southeast of the II 

 Street Bridge, 1915 (/. B. S. Norton); C. nigra L., Daniels Road, July, 1914 (Steele): 

 C.jaceaL., Franklin Park and Pinehurat. None of them, probably, is established. 



Bracts ending in long stout spines; heads sessile; leaves with spiny lobes and teeth. 



1. C. calcitrapa. 

 Bracts not spiny; heads stalked; leaves not spiny. 



Stem leaves all divided into linear lobes 2. C. maculosa. 



Stem leaves all or mostly entire 3. C. cyanus. 



1. Centaurea calcitrapa L. Star thistle. 

 Abundant in waste ground at Alexandria; occasional about Washington. May- 

 Sept . Native of Eur. ; adventive in the eastern U. S. 



2. Centaurea maculosa Lam. 



Collected near Mullikin and at Franklin Park; perhaps not established.' July-Aug. 

 Native of Pmr.; occasionally adventive in the eastern U.S. 



3. Centaurea cyanus L. Corn-flower. 

 Occasional in waste ground and grain fields. Native of Eur.; often cultivated for its 



showy blue, pink, or white flowers 



Known also as bluebottle and bachelor's-button. 



SUMMARY OF THE LARGER GROUPS, WITH NUMBERS OF GENERA 



AND SPECIES. 



FTERrDOPHYTA. 



Ophioglossaceae 



( >smuiuhiceae 



Schizaeaceae 



Polypodiaceae 



Equisetaceae 



Lycopodiaceae 



Selagmellaceae 



Isoetaceae 



GYMNOHPERMAE. 



Pinaceae 



MONOCOTYLEDONEAE 



Typhaceae 



Sparganiaceae 



Potamogetonaceae 



Naiadaceae 



Alismaceae 



Vallisneriaceae 



Poaceae 



Cyperaeeae 



Araceae 



Lemnaceae 



Xyridaceae 



Eriocaulaceae 



Commelinaceae 



Pontederiaceae 



Juncaceae 



Genera 



2 

 1 

 1 



17 

 1 

 1 

 1 

 1 



1 

 1 



2 

 1 

 :*. 

 2 



">7 



13 



5 



:\ 

 i 

 \ 



2 



2 



Species. 



4 

 3 



1 

 36 



2 



:\ 



\\\ 



2 



9 



2 



1 86 



1 55 



(i 



3 



2 



2 



4 



3 



16 



MONOCOTYLEDONEAE — Con. 



Melanthiaceae.. 



Liliaceae 



Convallariaceae. 



Smilacaceae 



Amaryllidaceae. 

 Dioscoreaceae... 



Iridaceae 



Orchidaceae 



DICOTYLEDONE AE . 



! Paururaceae 



J Salicaceae 



Myricaceae 



| Juglandaceae . . . 



| Betulaceae 



: Fagaceae 



I T'lmaoeae 



Moraceae 



I'rticaceae 



Loranthaceae 



Santalaceae 



Aristolochiaceae . 



Polygonaceae 



Chenopodiaceae . 



A maranthaceae . . 



Ailioniaceae 



Phy tolaccaceae . . 



Aizoaceae 



Portulacaceae.... 



Genera. 



7 

 7 

 6 

 1 

 l 

 1 

 3 

 16 



Species. 



9 



1 r > 

 8 

 (i 

 1 

 2 

 9 



31 



1 

 15 



2 

 7 

 6 



2:i 

 5 

 4 

 8 

 1 

 1 

 2 



28 

 7 

 8 

 1 

 1 

 1 

 3 



