NOTES ON PONDWEEDS. 187 



6. S. pulvinare. Masdevallia pulvinaris Rchb. f., in Gard. 

 Chron., 1880, i. p. 200.— Columbia ? 



7. S. punctatum. Masdevallia punctata Eolfe, in Gard. Chron., 

 1888, ii. p. 323. — New Granada ? Closely allied to S. awertw- 

 folium. 



8. S. swerti^folium. Masdevallia swertiafolia Rchb. f., in Gard. 

 Chron., 1880, ii. p. 390. Discovered by Lehmann on the Western 

 Cordillera of New Granada. 



9. S. verrucosum Pfitzer, in Engl, and Prantl., Natiirl. Pflan- 

 zenfam., i. Orch. p. 139. Masdevallia verrucosa Rchb. f., in 

 Linnasa, xxii. (1849), p. 819. Pleurothallis verrucosa Rchb. f., in 

 Bonplandia, ii. (1854) p. 24. — New Granada, near La Baja, in the 

 province of Pamplona, at 8200 feet elevation, Funck and Schliin, 

 No. 1439. 



NOTES ON PONDWEEDS. 

 By Alfred Fryer. 



Potamogeton decipiens Nolte. — Bootstock striking deeply into 

 the soil with strong far-spreading stolons ; stem stout, round, 

 simple below, sparingly branched above the middle ; all the 

 branches spreading ultimately at the surface of the water, with 

 widely diverging branchlets. Leaves all submerged, semi-amplexicaul, 

 or upper sessile; alternate, opposite at the base of the peduncles 

 only ; lowest leaf very rarely reduced to a short strap-shaped 

 phyllode which is rounded at the tip and mucronate, or with a 

 narrow lamina attenuated towards each end. Ordinary leaves all 

 similar, oblong, strap-shaped, rounded and mucronate at the apex, 

 or narrowed and apiculate, upper rarely orbicular, flat, or involute 

 at the base, sometimes longitudinally folded and recurved, with 3 

 principal ribs on each side of the midrib, the two outer springing 

 from the base of the leaf, the inner from, the midrib itself, with fainter 

 intermediate ribs connected by numerous conspicuous transverse 

 veins. Stipules blunt, stout, long ; those on the upper branchlets 

 longer than the internodes ; herbaceous, persistent ; those at the 

 base of the stem sometimes dilated towards the tip into a leaf-like 

 lobe, those at the base of the branches often bearing a conspicuous 

 sessile leaf 1-2 in. long. Peduncles not swollen upwards, often 

 scarcely thicker than the stem ; 2-3 times longer than the flower- 

 spike, subtended by two opposite leaves, terminal becoming lateral 

 by the growth of the branch. Flower-spike 1 in. long, barren; 

 abortive drupelets resembling those of P. perfoliatus. Colour of the 

 whole plant bright green, or brownish green, drying darker. 



P. decipiens, as at present accepted by authors, is probably not 

 a true species, but an aggregate of hybrids between P. lucens 

 (female) and P. perfoliatus (male), or possibly sometimes with P. 

 Zizii as the seed-bearing parent. It is very closely related to the 

 larger forms of P. nitens, such as f. pralongifolia of Dr. Tiselius. 

 Some botanists have suggested that it is lucens x prcdongus, but 



