i oe AN ae ee ee. 
BRIEFER ARTICLES. 
Compass Plants.—I was among the first to be interested in the pe- 
culiar twisting of the leaves of the Si/phium Jlaciniatum, and my papet 
published in 1865, in the “Proceedings of the Academy of Natural Set- 
ences of Philadelphia,” shows how closely the curious plant attracted 
me. There were some lingering doubts about the “ polarity” of the 
leaves, till one day, when in St. Louis, my good friend Dr. Engel- 
mann, took me to a waste lot in that city, where Lactuca Scariola had 
just secured a foothold. He was a strong believer in polarity, and I 
gave up. Ihave, however, continued for a quarter of a century to look 
for additional facts. It is surprising, if we look closely, how many 
plants we shall find twisting as Mr. Foerste describes the leaves of 
some doing (this journal, azte, p. 35). Possibly the best of all to study 
are Gaura parviflora, and Chrysopsis villosa. Witha prepossession Im 
favor of “polarity” I used to think I saw in these good evidence 
thereof. Continuous and careful watching proved I was wrong: I 
have long had to abandon this hypothesis in all except the Silphium, 
as a single plant in my garden is not a fair test. Not seeing them 10 
any quantity I have to be simply an agnostic in regard to its “tendency 
to evade the direct rays;’ and many other suggestive explanations I 
have also had to abandon. : 
A few years ago, I found myself at Gettysburg a day ahead of time, 
Of course it was devoted to botany. Lactuca Scariola had go ther 
before me, and was in considerable quantity in some portions of that 
sacred ground. I walked and sat among them a couple of hours, de 
termined it should give up to me the secret of its upturned leaves 
With some strong shoots of species of Solidago before me, wa 7 
minded of a strong but cordial controversy by letter, extending yes : 
some time, that I had had in the past with Dr. Asa Gray, J affirming 
that the leaves of plants do not originate at the nodes 
they appear to spring—a point, by the way, I can more strongly de 
to-day. It could be easily seen, by these Solidago stems, 
blades had twisted pentamerously around the stems from eee 
hite point below, the edges of each leaf overlapping, just as pape se 
laps when the confectioner twists a piece of paper into 4 “cornucop 4 
bag to hold the sweetmeats; and that-leaf blade, as we finally ae : 
understand the term, is the last crowning act of the spiral gon ae . 
this key it did not take long to open the Lactuca mysteTy: | ince 
of my quarter of a century of search seemed rewarded. 1 BAYS = 
used the key to the mystery in other plants, and the treasure bony 
as easily. It is the same answer all round. Zhe twist ihe? ogical 
@ somewhat prolonged effort of spiral growth, and of 10 phys 
value whatever. 
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