MIDDLESEX FLOKA. 



N. SYLVESTRE, R. Br. YELLOW CRESS. 



Medford, 1887 (F. S. Collins) ; Newton (C. J. Sprague; Man. 1859). 

 May-June. Nat. from Eu. 



N. palustre, DC. MARSH CRESS. 



Somerville, Cambridge, Framingham, Groton, et al. Rather com- 

 mon. May-July. 



N. ARMORACIA, Fries. HORSERADISH. 



Often found escaped, from cultivation. Apparently persistent. 

 May-June. Nat. from Eu. 



N. amphibium, R. Br. var. auriculatum, Reich. 

 Cambridge, rubbish-heap, 1884 (Walter Deane ; specimen in herb, 

 of). Adv. from Eu. 



"Pod elliptical or oblong, three or four times shorter than the 

 pedicel ; immersed leaves undivided, lanceolate, attenuate at both 

 ends, sessile ; upper leaves pectinato-pinnatifid or lyrate ; petals 

 longer than the calyx; var. auriculatum, DC. Leaves furnished 

 with small auricles at the base." Koch, Syn. Flor. Germ. 



DENTARIA, L. PEPPER-ROOT. 



D. diphylla, Michx. 



Arlington (E. Tuckerman) ; Belmont, specimen in the Boott herb. 



May. 

 D. heterophylla, Nutt. 



Lowell (Albert S. Guild; W. P. Atwood). Rare. Apr.-May. 



Adv. from the South. 

 *D. laciniata, Muhl. 



Belmont, near Railroad Station (Win. Boott). Apr.-May. 



CARDAMINE, L. 



C. rhomboidea, DC. WHITE SPRING-CRESS. 

 Medford and Belmont (F. S. Collins) ; Woburn (C. E. Perkins) ; 

 Framingham (Rev. J. H. Temple) ; et al. May. 



* C.jrhprnboidea, DC., var. purpurea, Torr. PURPLE SPRING- 

 CRESS. 

 Arlington, May 8, 1865 (Wm. Boott). 



C. hirsuta, L. SMALL BITTER-CRESS. 

 Common. May- June. 



C. hirsuta, L., var. sylvatica, Gray. 

 Melrose and Medford (F. S. Collins). May-June. 



ARABIS, L. 



A. hirsuta, Scop. HAIRY ROCK-CRESS. 

 Somerville (C. E. Perkins) ; June-July. 



