

T. Holm — Mollugo verticillata L. 525 



Art. XLIV. — Mollugo verticillata~L. ; by Theo. Holm. (With 

 nine figures drawn by the author.) 



In several respects our common Carpet-weed, Mollugo verti- 

 cillata L. is quite an interesting plant, and there are several 

 points in its structure, external as well as internal, which have 

 not been studied so far ; as a matter of fact, a number of our 

 commonest plants are actually but little known, and it so hap- 

 pens that Mollugo illustrates an excellent example of anisoph- 

 ylly, beside that the internal structure, of the leaf especially, 

 is somewhat anomalous when we compare the other members 

 of the Ficoidew, to which the genus is now generally referred. 

 For several reasons, which will be shown in the subsequent 

 pages, Mollugo is somewhat out of place in this family, which 

 contains so distinct and utterly different types as Tetragonia, 

 Aizoon and Mesembryanthemum ; moreover, Jussieu,* who 

 established the family Ficoidem, did not include Mollugo. 



Now in regard to anisophylly, which is illustrated so very 

 plainly in this species of Mollugo, the term was first proposed 

 by Wiesner, and expresses the unequal size of leaves of plagio- 

 tropic shoots in accordance with their position on the upper or 

 lower face of the shoot ; more frequently the leaves of the 

 upper face are of a smaller size than those of the lower, but 

 the opposite case is known also. Anisophylly occurs in very 

 many plants, cryptogamous as well as phsenogamous, herbs 

 as well as trees ; it may be characteristic of certain genera, or 

 only of certain species within the same genus.f It is readily 

 appreciated that light must be one of the factors to produce 

 anisophylly, especially when we consider the branches of a tree 

 where the peripheral leaves are usually much larger than the 

 inner ones, on account of their fuller exposure to the sun- 

 light. However, this is not always the case, and, as stated 

 by Goebel (1. c.) there may be several other factors, beside 

 light and position to horizon, that produces anisophylly. 

 Already in the buds of Aesculus anisophylly may be observed, 

 thus a long time before they open, and etiolated specimens of 

 Goldfussia and Elatostemma exhibited the same degree of 

 anisophylly as other specimens grown under normal conditions. 



jSTow in regard to Mollugo, the foliage is in the Synoptical 

 Flora of jSTorth America^: described as " pseudo-verticillate," a 

 term on linguistic grounds inadmissible ; moreover the leaves 

 are opposite, and very plainly so. The leaf-arrangement, as 



* Genera plan tarum, Paris, 1789, p. 315. 



f Compare Goebel: Organographie der Pflanzen, Jena, 1898, p. 85 seq., 

 where several eases are described, and the most important literature cited. 

 t 1895-1897, p. 257. 



