PLANTS OF WESTERN LAKE ERIE. 
73 
difference in the structure of these two, except that the emersed leaf is much better 
provided with ribs, which, besides being more numerous, are stronger than those in 
the floating leaf. 
ROOTS AND RHIZOMES. 
Some aquatic phanerogams have so completely adapted themselves to a watery 
medium that they have dispensed with roots except in the germinating seedling, and 
in Ceratophylluin even these are almost wholly suppressed. With the exception of 
Utricularia , Ceratophyllum, , and Wolffia , all phanerogams in our waters produce some 
roots. In Lemnacece these are slender organs serving to keep the plant in position 
on the surface. The rooting aquatics, as the Potamogetons and Myriophylhum , are 
provided with roots that, according to Schenck, 1 have no purpose save to anchor the 
plant. Hochreutiner 2 has endeavored to show that the roots of Potamogeton have 
another function. In experiments tried by him at Geneva, it appeared that eosine 
solution was absorbed by the roots and passed up the stem much more readily than 
it passed through the leaves. If this function of the roots of aquatics can be proven, 
it will help to explain some observations referred to under the discussion of the soil 
samples. 3 
ROOTSTOCKS. 
Most aquatics and swamp plants have rhizomes or running rootstocks by which 
the species often spreads over considerable areas. On Gibraltar Bar the runners of 
Potamogeton heterophyllus ramify in all directions, and specimens of Potamogeton 
lonohites were collected at Sandusky showing extensive runners bearing buds at their 
ends. Heteranihera graminea has long black rootstocks. The thick rootstocks of the 
Nymphcmceaz buried in the mud give rise year after year to leaves and flowers and 
produce an abundance of strong fibrous roots. Sparganiurn eurycarpum , Sagittaria 
latifolia , Typha latifolia, Juncus torreyi , Scirpus pungens , and S. lacustris , among 
swamp plants, were specially examined for root systems. All are well supplied with 
running rootstocks, those of the species of Typha and Soirpus being particularly 
strong and widely spreading. Probably many square feet in an association of Soirpus 
and Typha are occupied by the plants of one system, each plant connected with all 
others of its species by the thick rhizomes. (See pi. 14, figs. 1—4; pi. 16, fig. 1; pi. 
17, figs. 4, 5. Typha , Nupha/r , Potamogeton , Juncus , Soirpus, Sparganiurn.) 
REPRODUCTION, PROPAGATION, AND WINTERING. 
In most aquatics the reproductive organs show the influence of the medium less 
than any other part of the plant. Such typical aquatics as TJtricularia produce 
showy flowers and the seeds ripen above water. Most aquatics, however, ripen their 
1 ScKenck, H. Die Biologie tier Wasscrgewiichse, Bonn, 1886. 
2 Hochreutiner, Georges. Etudes sur les phanerogames aquatiques du Rhone et. du port Geneve. (Revue gen. de Bot., 
t. vin, p. 158.) 
3 Since writing the above, Mr. R. H. Pond, while a special assistant to the United States Fish Commission, has 
investigated the relation of water plants to the solid substratum. A summary of results has been published in Science, 
vol. xni, No. 320, February 15, 1901, and is in part as follows: 
"1. Plants rooted in soil exceed in vegetation and dry weight plants rooted in sand or merely suspended. 
“2. Plants rooted in sand or merely suspended contain starch, calcium, and magnesium in excess, while they are 
lacking in nitrogen, potash, and phosphoric acid. 
“3. Lithium nitrate is absorbed by the roots and conducted to the upper portions of the plant, where it may be 
detected with the spectroscope.” 
These results confirm the work of Hochreutiner and justify the views expressed on page 70 as to the importance of 
the soil for the growth of aquatics. 
