34 AQUATIC PLANTS 



than Sagittaria. Also the plant tends more to rise vertically in undulating 

 lines, which produces a very pleasant decorative effect, being of a less 

 spreading contour than Sagittaria. The leaves may also be identified 

 by the margins being of a slightly different shade of green. By reflected 

 light the margins appear the darker, but if held up to transmitted light, 

 the centre is the darker. Vallisneria is probably without a superior as an 

 oxygenator. For use in large aquaria, particularly where artistic effects 

 are striven for, it is without an equal. The aquarium shown in colors 

 on page 111 is featured principally by this plant, although printing 

 ink falls short of giving an adequate idea of the radiant, silky green leaves. 



For some years American aquarists depended upon plants gathered 

 locally from rivers, creeks, mill races, etc. Owing to the long-established 

 habit of dying down to the tuft in winter, the plant had a strong tendency 

 to keep to the schedule, even when kept in a warm aquarium over 

 winter. In order to overcome this difficulty a search was made for a 

 stock growing in a climate without severe winters. This plan was suc- 

 cessful. We were fortunate enough to secure a small stock from Italy 

 which, by careful propagation and distribution among leading aquarists, 

 has now multiplied itself into millions. There is every reason why it 

 should establish itself in further favor among those having large or fairly 

 deep aquaria. It grows and multiplies constantly and the runners lie 

 close to the bottom, not requiring to be pushed down like young Sagit- 

 taria plants. Contrary to the views of some writers, we advise against 

 deep planting. It is important that the crown be not covered, but just 

 at the surface. The plant is not well suited to small aquaria, as it grows 

 from 18 to 36 inches, according to conditions. If closely confined it is 

 likely to get into a tangled mass whenever a fish has to be caught. 

 Allowed to rise to the surface and then extend horizontally on it for some 

 distance it produces a luxuriant picture. Rising from either end of the 

 aquarium and trained over the surface towards the centre, Vallisneria 

 makes the best of frames to show off the brilliant colors of the fishes. 

 The sexes are separate in Vallisneria, fertilization taking place in a 

 peculiar manner. The female flower, small, cup-shaped and white, floats 

 at the end of a long spiral scape on the surface of the water. The male 

 flower on another plant comes only a short distance from the crown. It is 

 a case containing pollen balls. When the case splits the pollen floats to 

 the top, where, by the action of wind, insects or other chance, fertilization 

 is accomplished. Few of these plants in the aquarium start from seed. 

 In propagation by runner only one sex appears along a line, males and 

 females producing only their own kind. The first plants imported were 

 all females. No males were seen for several years. These were likely 

 propagated from the seeds. 



