POTASH FROM KELP. 15 
mediate between the two types, sometimes grading more or less into 
the latter. Figures 6, 7, and 8 show these environmental types. 
In the third type the branches assume a horizontal position and 
send down numerous hapteres from the lower side. These creeping 
stems or “rhizomes” spread from rock to rock, rooting nearly to the 
tip, and thereby anchoring them- 
selves very firmly, but are never 
centrally located. The fronds rise 
from around the edges of such a 
clump. The hapteres never have 
to grow far to reach their support 
if the plant is growing on a suit- 
able bottom. As the center dies 
out, branches of the rhizomes grow 
in to take its place. When torn 
up by storms, this type comes 
ashore with pieces of the holdfast 
1 or 2 feet in diameter. Theoret- 
ically its hfe and the extent to 
which it may spread are unlim- 
ited. It appears to produce a 
shorter frond, with smaller leaves, 
than the typical WM. pyrifera, but 
because of the immense number of 
fronds sent up it makes a very 
heavy mat. This type has been 
found all along the southern coast, 
but in greatest-abundance near Re- 
dondo. It seems to affect shallower 
water than the other forms, and 
probably is an important compo- 
nent of the kelp beds that are most 
heavily matted toward shore. 
There is no recognizable differ- 
ence between the floating parts of 
this plant and those of the typical 
M. pyrifera. The rhizome-form- 
ing type is especially well exem- 
plified by the shore Macrocystis 
found in or just below tidewater 
on the coast of central or northern 
. . 5 <a 
California, a clump of which, ap- (ba) 
parently from one original plant, 
may cover every bowlder over a , 
, 5 F 1 y 7 F j 
space 30 feet wide and may persist Fig. 7.—Rough-water form—cyst and 
for many years. Its fronds are stipe parallel. 
short, 15 to 30 feet, its rhizomes are 
over an inch wide, flat, and sharply differentiated from the ascending 
stipes. The most violent storms seem able to tear off only small 
fragments of it, and a patch completely stripped of fronds in winter 
usually renews itself the following summer. 
