1913 FOR DUCKS IN NORTHERN ONTARIO. 9 



much thicker. The seed is then dark brown in color and is mature. The pods sink 

 still deeper in the water and finally disorganize, setting free the seed which is 

 drifted from place to place to establish fresh colonies of the plant. The mature seed 

 is packed with starch and very nutritious, as is also the pod itself. 



The double method of propagation of this plant enables it to establish itself 

 very rapidly and practically ensures its permanence once it is planted in a given 

 region. 



The Potamogetons, or Pond-weeds, as they are commonly called, sometimes 

 grow completely submerged like the wild celery, but usually some of the leaves come 

 very near the surface or may even float on the water. They all 'have a long slender 

 stem by which they are attached to the bottom; this stem may be leafy or devoid of 

 leaves. 



In the so-called Floating Pond-weed (Potamogeton natans), illustrated in 

 Fig. 2, the lower leaves on the stem are very much reduced in size, while the upper 

 ones are large and floating. They have usually a heart-shaped base where they 

 join the leaf stalk. This stalk, too, is attached in a peculiar way to the blade 

 looks as if it were jointed. It usually bends slightly to one side instead of coming 

 straight from the base of the leaf. Where the leaf stalk is attached to the stem 

 there is a structure (a stipule) like a grass leaf, which in the autumn is much 

 frayed into long colorless threads. The seed ripens in September, but persists for a 

 long time in the fruiting head. This is from one to two inches in length, and 

 since usually most of the seeds in a head mature and each seed has a good store of 

 starch in it, the plant affords valuable food. 



Floating Pond-weed can be propagated by seed. If the seed is found to float 

 when collected, it can be embedded in balls of clay and will then sink when thrown 

 into the water at the desired places. 



Figure 3 is of the Various-leaved Pond-weed (Potamogeton heterophyllus). 

 In this form there are two very distinct types of leaves. The upper ones are more or 

 less oval in outline. They terminate in a little tooth-like projection. These leaves, 

 though ordinarily called floating leaves, do not usually rest on the surface of the 

 water but are slightly submerged. The lower submerged leaves are about the same 

 length but much narrower and contracted at the base into a short stalk (see Fig. 

 3.) In some plants there are none of the upper type of leaves present, the whole of 

 the leaves being of the type of the lower ones. Such plants are found growing along 

 with the others. The stem is very slender, somewhat flattened, and usually much 

 branched below. The stalk of the fruiting head is much thicker than the stem or 

 other branches. The fruit and seed of this form are not more than half the size of 

 those of the Floating Pond-weed described above. It ripens its seed in September 

 and October. In should be propagated in the same way as Potamogeton natans. 



The Clasping-leaved Pond-weed (Potamogeton perfoliatus) never has any 

 floating leaves. There is, however, considerable variation in the shape and size of 

 the leaves which occur very r.bundantly on the much-branched stem. In all cases 

 the leaf has a heart-shaped base, which embraces the stem. Usually it terminates 

 in a long slender point (see Fig. 4). The leaf, too, is always more or less crinkled. 



This plant has a very effective method of propagation, as^de from reproduction 

 by seed. As it grows the older parts die away and the young branches, with their 

 smaller leaves, can float away and form new plants. This is especially true of the 

 plant during the winter. No old stems and leaves survive, and in the early spring 

 only the small-leaved type, Fig. 4a, is to be found. Towards the autumn, however, 

 the long-leaved forms are abundant. These long leaves, however, are attached 



