Angewandte Botanik. 187 



•& 



roots possess a contractile exodermis. In the rhizome is no endoder- 

 mis, and no pericycle either; the mestome-strands are mostly lepto- 

 centric. The stem above ground has no endodermis, but a closed 

 sheath of stereome surrounding two almost concentric bands of 

 collateral mestome-strands. The leaf-struciure is isolateral, stomata 

 occurring on both faces of the blade, and the chlorenchyma being 

 homogeneous throughout, completely destitute of palisade-cells. AU 

 the veins, including the midvein, are embedded in the chlorenchyma, 

 and are supported by small arches of stereome. Theo Holm. 



Holm, T., Medicinal plants of North America. 85. Hepatica 

 triloba Chaix. var. Americana DC. (Merck's Report. XXIII. p. 

 293—295. f. 1 — 14. Dec. 1914.) 



In North America Hepatica triloba Chaix is only represented 

 b)'^ the variety Americana DC, densely villous, and with the lobes 

 of the leaf very obtuse; Hepatica acutiloba DC. occurs, also, on this 

 continent; in both the leaves are sometimes five-lobed. The seedling 

 is described by Fr. Hildebrand, and it is interesting to notice 

 the difference from Anemone in which the plumule is subterranean 

 and lacks the protection by scale-like leaves. In Hepatica the plu- 

 mule is above ground, surrounded by several membranaceous, 

 Scale like leaves, and the typical leaf, the three-lobed, does not 

 appear until the next season. A few anatomical features deserve 

 attention. The roots possess a contractile exodermis; the rhizome 

 Shows no endodermis, and no pericycle either, and the same is the 

 case with the flowering scape. Stomata occur on both faces of the 

 leaf-blade, but are, however, most abundant on the dorsal; there 

 is a layer of short, plump palisade-cells covering an open pneumatic 

 tissue; all the veins are embedded in the chlorenchyma, and only 

 the primaries have a small support of collenchyma. 



Theo Holm. 



Holm, T., Medicinal plants of North America. 86. Junipe- 

 rus Virginiana L. fMerck's Report. XXIV. p. 6—9. f. 1 — 14 Jan. 

 1915.) 



The seedling has only two cotyledons, linear and obtuse, and 

 the primary shoot as well as the lateral branches bear only acicu- 

 lar, spreading leaves, in whorls of four on the primary axis, but 

 in pairs on the axillary branches. Characteristic of the root-structure 

 is the development of several concentric bands of stereome (secon- 

 dary; outside the leptome; similar bands of stereome occur, also, 

 in the twigs. In respect to the structure of the leaves, the awl- 

 shaped leaves of the seedling possess a stereomatic hypoderm in the 

 convex, dorsal face, and the stomata are confined to the ventral 

 face of the blade; two to three layers of palisade-cells are located 

 inside the hypoderm. In the scale-like leaves of the mature tree 

 there is, also, a hypoderm, but the pallisade-tissue foUows here the 

 entire outline of the leaf, surrounding an open pneumatic tissue. 

 On both sides of the midrib is a group of tracheids provided with 

 projections from the wall extending nearly or quite across the cell- 

 cavity, somewhat after the manner of beams, hence the term "cross- 

 beamcells" or "trabecular tracheids" may be applied to these; they 

 were detected by Mo hl. Theo Holm. 



