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The Chareae of North America 
By CHARLES Bupp ROBINSON 
The Characeae form a group of slender aquatic plants of very 
wide distribution, inhabiting fresh, brackish, or very rarely salt 
water. They are of varied size and habit, their color depending 
to a considerable extent upon the absence or presence of incrusta- 
tion, ranging thus from an intense bright-green or dark-green to 
grayish. They generally form large masses and grow submerged 
at depths up to at least 12 meters, but most often 2 meters or less, 
frequently in pools of such a nature that they completely dry at 
some seasons, the plants accordingly being subjected to extreme 
changes in environment. They are often very fragile, both when 
living and dried, whence one of their common names, Brittle- 
worts; they are also frequently called Stoneworts. Most forms 
have an unpleasant odor, resembling that of sulphuretted hydrogen. 
They constitute an extremely natural group, with no very near rela- 
tives. Among themselves with a comparatively simple structure 
they present a great variety of differences, which have made their 
specific limits difficult to ascertain. 
Sexual reproduction takes place by means of antheridia and 
odgonia. The odgonium originates as a naked cell which elongates 
and divides by horizontal walls into three, of which the apical be- 
comes ultimately the odspore, and the middle or stalk cell under- 
goes no further division, but is usually concealed in the developing 
sporocarp. The basal cell of thethree forms five superficial cells, 
from each of which a cell begins to grow upward to envelop the 
odsphere. Each enveloping cell divides into an upper and a lower; 
the latter elongates and becomes spirally twisted, but does not again 
divide. 
These cells of the lower tier closely invest the odsphere, which 
after fertilization b the odspore, their lines of contact showing 
in later development asa series of more or less distinct ridges or striae 
upon the spore. The number of striae thus seen is accordingly 
five times the number of turns made by the spiral envelope in the 
length of the spore, this number ranging from one to three or very 
rarely more, though nearly definite for a given species. In prac- 
tice it is always more convenient to count the striae. The five cells 
