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. 



Natiek (Rev. Thos. Moi'ong, specimen in herb. of). 

 P. pauciflorus, Pursh. 



Medford (Wm. Boott) ; Cambridge (Pev. Thos. Morong). 

 P. pusillus, L. 



Common. 

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



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



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



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



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



bnds 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) ; Medford (Win. Boott) ; Concord 



(Walter Deane). 



Triglochin, L. 



T. maritlmum, 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/E. 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. 



