MIDDLESEX FLORA. 101 



P. CRISPUS, L. 



Spy Pond, Arlington ; probably introduced (C. E. Faxon). 

 P. zosteraefolius, Schum. (P. compressus, L., Man.) 



Cambridge and Natick (Rev. Thos. Morong). 

 P. obtusifolius, Mert. & Koch. 



Natick (Rev. Thos. Morong, specimen in herb. of). 

 P. pauciflorus, Pursh. 



Medf ord (Wm. Boott) ; Cambridge (Rev. Thos. Morong) . 

 P. pusillus, L. 



Common. 

 P. pusillus, L., var. polyphyllus, Morong. 



So. Natick and Fresh Pond, Cambridge (Rev. Thos. Morong). 



"A dwarf form, 3-5 inches high, divaricately branching from the 



base, and very leafy throughout ; leaves very obtuse, not cuspidate, 



3-nerved ; non-flowering, but abundantly provided with propagating 



buds which are formed on the thickened and hardened ends of the 



branches, and closely invested by imbricated leaves." Morong in 



Bot. Gaz., Vol. V., No. 5. 

 P. pusillus, L., var, tenuissimus, Mert. & Koch. 



Natick (Rev. Thos. Morong). 

 P. gemmiparus, Robbins, (P. pusillus, L., var. gemmiparus, 



Man.) 



Mystic Pond (E. Tuckerman) ; So. Natick (Rev. Thos. Morong). 

 P. Robbinsii, Oakes. 



Fresh Pond (E. Tuckerman) ; Medf ord (Win. Boott) ; Concord 



(WalterDeane). 



TRIGLOCHIN, L. 



T. maritimum, L. ARROW-GRASS. 

 Common in salt marshes. June-July. 



SCHEUCHZERIA, L. 



S. palustris, L. 

 Ashby (W. H. Manning) ; Tewksbury (B. D. Greene). June-July. 



ALISMACE>. WATER-PLANTAIN FAMILY. 



ALISMA, L. 



A. Plantago, L., var. Americanum, Gray. WATER-PLANTAIN. 

 Rather common. June-July. 



ECHINODORUS, Rich., Engelm. 



E. parvulus, Engelm. 



Cambridge (James); Winter Pond, Winchester (Dr. C. W. Swan). 

 July-Aug. 



