70 FLORA ORCADENSIS. 
one of the small lochs along the road from Hoy to 
Rackwick ; Rev. E. 8. Marshall found it. My speci- 
mens are from this. (See “Scottish Botanical Review,” 
April 1912.) 
OrpER LI.—_LEMNACEA. 
Genus CLXXXVIIL.—LEMNA (Linn.) 
390. L. minor (Linn.), Duckweed. 
This plant was reported at first by Dr Maenab, 
but was subsequently considered doubtful. My speci- 
mens were gathered in bog below Ocilster, Holm. 
G. W. Scearth and I found it in a bog in Cross, Sanday. 
It is found on stagnant water. 
OrDER LIT.—NAIADACEA. 
Genus CLXXXIX.—TRIGLOCHIN (Linn.), Arrow-grass. 
391. T. paALUSTRE (Linn.), Marsh Arrow-grass. 
Common. 
392. T. MARITIMUM (Linn.), Seaside Arrow-grass. 
Common on salt marshes. 
Genus CXC.—POTAMOGETON (Linn.), Pond-weed 
393. P. NaTANS (Linn.), Broad-leaved Pond-weed. 
Fairly common. 
Near Maeshowe and Loch of Harray (Dr Boswell). 
My specimens are from F lotta, in Birsay. The 
Orkney plant has unusually long peduncles. 
394. P. HETEROPHYLLUS (Schreb.), Pond-weed. 
Common, 
