530 T. Holm — Mollugo verticillata L. 



beside a single stratum of thinwalled parenchyma bordering 

 on the leptome (L. in rig. 5). We find in the stele about twenty, 

 distinct, collateral mestome-strands separated from each other 

 by narrow rays of thinwalled parenchyma, and enclosing a 

 solid pith, which is not excentric; it is only in very thick stems 

 that some of the internodes (but not all) may show an excentric 

 structure so far as concerns the stele, but not the cortex. The 

 structure of the fruiting pedicel agrees with that of the inter- 

 node described above, but we notice here the presence of small, 

 obtuse hairs (fig. 9) rilled with a greenish brown, granular 

 substance ; moreover the stele contains only four mestome- 

 strands. 



Before leaving the stem we might mention that in vigorous 

 specimens the basal nodes are frequently swollen, and distinctly 

 so ; this is, however, not due to the presence of collenchyma, 

 as was expected, but simply to an increase of strata in the cor- 

 tex. — "While thus the structure of root and stem is very simple, 

 we observe in the leaf several points which are quite interest- 

 ing. It is, for instance, strange that the leaves, although being 

 held in a horizontal position, possess stomata on both faces, 

 and, at the same time, the chlorenchyma illustrates a typical 

 dorsiventral structure with palisade-cells on the ventral, and 

 with a pneumatic tissue on the dorsal. 



The cuticle is thin, and the lumen of the thinwalled epidermis 

 is wider on the ventral than on the dorsal face, but there are 

 no papillae ; viewed in superficial sections, the lateral walls of 

 epidermis are undulate on the dorsal, but less so on the ven- 

 tral. Stomata abound on both faces of the blade ; they are 

 level with epidermis, and lack subsidiary cells. Hairs like 

 those observed on the pedicels (fig. 9) occur along the midrib 

 on the dorsal face, and at the base of the leaf-blade. There 

 are two strata of typical palisade-cells with single, quite large, 

 rhombic crystals of calcium oxalate, besides styloids ; spheric 

 crystals were observed in material preserved in alcohol, and 

 they were located beneath the stomata. No collenchyma and 

 no stereorne is developed, but the veins have large-celled paren- 

 chyma-sheaths (P. in figs. 6-8) ; the midrib is the broadest of 

 these (fig. 6) ; it is arch-shaped in cross-sections, and the hadrome 

 contains several narrow spiral-vessels ; the lateral veins are 

 much thinner (figs. 7-8) and consist only of a few leptome-cells 

 and a single spiral-vessel, or of leptome alone as shown in figure 

 8, which represents the marginal mestome-strand. The water- 

 storage tissue is very poorly developed as a few strata above 

 the midrib, between the palisades and the parenchyma-sheath. 



From an anatomical point of view Mollugo verticillata is 

 very distinct from the " other" members of Ficoidece as 

 described by Solereder (1. c.) : Mesembryanthemum, Tetra- 



