218 BOTANICAL GAZETTE [seprmcm 
THE GROWTH OF RAMALINA RETICULATA. 
(WITH ONE FIGURE) 
RAMALINA RETICULATA (Noehd.) Krempelh., so characteristic of the 
coast valleys of California, offers to the plant physiologist a particularly 
fruitful field for the study of the growth, apothecial development, and 
dissemination of lichens. 
. TUCKERMAN states" that his longest specimens were a little more than 
a foot in length, and that the widest per- 
forated expansions exceeded 20™™, Just 
what dimensions this plant may attain I 
am not prepared to state, but I agree with 
Dr. Peirce that it is probably the largest of 
our North American lichens. Specimens 
four and five feet long are common on the 
trees about Stanford University, their 
widest perforated expansions reaching two 
feet or more. Specimens in my herbarium 
t—Ramalina reticulata: vary from those of the most delicate lace 
like structure to those having broad, ut 
perforated expansions 25 to 407™ in width, 
dimensions much greater than the largest 
perforated specimens seen by Tuckerman. Usnea longissima Ach. attains# 
length of eight or nine feet on the redwoods of the Santa Cruz mountains, but 
Fic. 
A, thallus branch; B, lobe; C , knot 
of silk used to designate measured 
lobes. 
the thallus is so slender that its real size is much less than that of Ramalina 
reticulata. ~ : 
The plant is evidently such a rapid grower that last September a — 
of measurements were made, at the suggestion of Dr. G. J. Peirce, in ore 
to obtain some definite results. The lengths in the column under Septem 
ber are the measurements made September 25, 1903; those unde 7 
were made May 5, 1904, an interval of seven months and ten days. ‘ 
winter rains did not begin for nearly two months after the measureme? 
Were made, and ceased two or three weeks before the lichens were pe 
ured, so that most of the growth was confined to a period of wer 
months, During the late winter and early spring growth must eee 
both rapid and continuous, since for nearly two months it rain 3: 
daily, the temperature also being favorable for growth. Jobes 
The thallus was measured from the point of attachment, a a 
measured being marked by a knot of silk thread, the weight i. 
so inconsiderable as to have no effect on the growth. The meas 
t Synopsis N. A. Lichens, part 1, p. 22. 
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