120 The Botanical Gazette. {March, 
of the light salmon-colored corolla. I describe the most extreme 
form as 
Var. diffusa, n. var.—Taller, stems much more slender, 75-100" 
high, much branched; branches long below, very short above: leaves 
linear, shorter, scattered: flowers in much smaller heads, at ends of 
branches, and summit of stem: glandular and cellular pubescence Very 
thick upon the calyx, bracts, and upper leaves, and sometimes the en- 
tire upper portion of plant is pubescent.—A. IsaBEL MucrorpD, Her- 
barium Like Forest University. 
Frost Plants.—Prof..Lester F. Ward’s observations on the “Frost 
freaks of the dittany,” in the Gazetre for April, 1893, occasioned much 
interest, since the phenomena illustrate one form of the movement 
of water in the plant stem. I have elsewhere! made a lengthy review 
of the literature of the frost plants and take occasion to call attention 
to the following references which may be accessible to the readers of 
the Gazette. ; 
Prof. Ward called my attention to the fact that the frost crystals : 
of Cunila and Helianthemum were noted by Dr. Darlington.* The 
first observation of frost phenomena recorded is that of Stephen 
Elliot on the stem of Conyza difrons (now Pluchea bifrons). St 
John Herschel noticed a similar formation on the stalks of heli ; 
trope and thistle.* Prof. John Leconte made an extended study ‘ 
of the frost crystals of Pluchea camphorata and P. bifrons, 0 1848, # 
along the coast of South Carolina and Georgia.® Prillieux his 
investigations on freezing in intercellular spaces described the forme © 
tion of radial ice plates by herbaceous plants.¢ These observations — 
were duplicated by Trecul at the same time, and Sachs has given ee | 
matter bearing upon this point.? In a recent number of this jour 
Professor Atkinson gave a note recording the fact that these phenom 
€na were seen by him in 1885-86,° while Professor Ward has fo ; 
that the frost freaks of the dittany are a matter of common inform 
tion In the locality in which his observations were made.° ot 
It seems established that the frost phenomena occur on plants whi 
have ceased growing, or are wholly dead; that the movement of i 
water upward through the stem and laterally is wholly physical yet 
ae of the University of Minnesota. 2; 30. 1894- ead 
*Flora Cestrica 350. 1837. 
‘Ledge tae . South Carolina and Georgia. 322. 1824- 
in ; os 
ompt. Trend. 70: i 8 
7Lehrbuch, 2 kak 0 vee 
*Bor. Gaz. 19: 40 1894. 
*Science 23: 66, 1894. 
