40 



saltness which they can stand scarcely exceeds ca. 2 p. c. Thej' require'for their 

 growtli, further, a still more protected place than the commou Zostera, aud none 

 of them go out to auy great depths; J. Reinke (1. c.) states that ZannichelUa aud 

 Potamogeton pectinatns occur to 5 meters deptli, and I have found the same piants 

 to ca. 4 meters depth. 



The piants spokeu of here are: Biippia, Zannichellia and Potamogeton pec- 

 tinatns L. Besides these, one may in very sligthly saline water, e. g. in firths and 

 creeks into which streams opeu, meet with others that cannot really be called 

 marine piants, thus Najas marina L., Myriopliyllu mspicatum L., Rammculns Bau- 

 dotii Godr. aud Scirpus pavulus R. & S.; these will not be diseussed here. 



2. Biippia nutritima L. resembles in its growth dwarf Zostera. There is 

 a creepiug rootstock, which is generally pale (whitish), and from this issue thread- 

 fiue 8 — 25 cm. long leaves with a lower, somewhat dilated sheath-part. Branches 

 issue from very many of the axils of the root-stock so that the Ruppia forms 

 a net-work in the sandy or soft bottom on which it grows. The branclies may 

 end in an inflorescence which consists of the flowers only, placed at the end 

 of a shorter or longer stalk; this stalk in the Ruppia growing in fairly deep water 

 is often very long aud reaches the surface, so that the flowers eau opeu in the 

 air. The pollen is so constructed that it eau Hoat on the water (the pollen graius 

 are curved and short, sausage shaped) and be carried by the wind to the stigma; 

 at the end of June I have seeu it iu such quautities at certain piaces in Guld- 

 borgsund that the water looked as if it were covered with a pale-yellow, flue 

 powder. Wheu the fertilisation is completed, the stalk curves itself up spirally, so 

 that the fruit will ripeu in the water. Iu other forms of the Ruppia the stalk is 

 always short, aud it must be supposed that fertilisation in these cases takes place 

 down in the water. 



The Ruppia grows in shallow water from the low water mark and to ca. 

 1 meters depth (perhaps 2 meters); it forms fairly extensive vegetations in a friuge 

 beyond the beach on almost all the coasts of our inner waters, if the place is 

 fairlj' protected. The most northern piaces, where I have seeu it, are in Hobro 

 and Randers Fjord, at Læsø, aud also in Stavns Fjord on Samsø; but it is especially 

 in the w^aters south of Zealand and Fuueu, rouud about the small islands, that it 

 occurs in large (juautities. The short and fairly deuse vegetation is of a dark 

 Ijrownish-green colour, aud resembles a grasslawn under the water, as the leaves 

 of the Ruppia are extremely flue (ca. 1 m. broad) and thread-like. 



;-). Zannichellia palustris L. occurs more rarely in large pure vegetations 

 tliau the Ruppia, but it may on the other band go deeper down in the water, to 

 4—5 meters, and seems to prefer softer bottom. Some shoots creep along or are 

 but little submerged in tlie ground, others rise more or less perpendicularly iu 

 the water. It has thread-flne, 2 — 8 cm. long leaves placed iu whorls of 2 — 4, 

 most often 3, at each joint of the stem. In the axils of the leaves, which have 

 uo sheath, we flud the small flowers, which couse(iueutly opeu aud are fertilized 

 down in the water. The fruits (generally 4 together) are crescent-shaped and thoruy 

 on the outside of the curve. 



Zannichellia is a trifle more sensitive as regards saline water; it lives in 

 the real brackish water, and is e. g. common in Kalvebodstrand, iu the Bøgestrøm 



