Angewandte Botanik. 607 



hyphae were only found in the exodermis. In the stem the cork 

 develops l'rom epidermis. The leaves shows several points of interest, 

 for instance that they are covered with unicellular, bent hairs; a 

 distinct hypoderm is present on the ventral face, and pertains to 

 the chlorenchyma. A steloid structure characterizes the midrib, there 

 being fourteen collateral mestome-strands arranged in a circular 

 band, enclosing a pith, and surrounded by a large colorless paren- 

 chyma with many resiniferous cells beside some irregulär, star- 

 shaped, hollow bodies of silica-incrustations. But otherwise the inter- 

 nal structure in general is very much like that observed in the 

 genus Liriodendron (Compare Merck's Report for August 1909.) 



Theo Holm. 



Holm, T„ Medicinal plants of North America. 59. Hama- 

 melis Virginiana L. (Merck's Report. XXI. p. 5—9. fig. 1—22. Jan. 1912.) 



"Hamamelidis cortex" is the bark and twigs of this plant, the 

 well known Witch-hazel. The bark was used by the North American 

 Indians as a sedative application to external inflammations, tumors 

 and piles, sore and inflamed eyes cet. However it seems doubtful 

 whether the plant really does possess any active physiological pro- 

 perties. The substance sold as hamamelin is a mixture consisting of 

 an evaporated alcoholic extract of either the leaves or the bark. 

 Several fignres show the floral and foliar organs, beside the anatomy. 

 In respect to the root-structure may be mentioned the occurrence 

 of stere'i'ds as well as sclereids in the secondary cortex; furthermore 

 that several of the libriform cells, especially in the innermost strata 

 of the hadrome rays, showed an inner thick, gelatinous layer more 

 or less separated from the lignified part of the cell-wall. There are 

 in the branches isolated Strands of pericyclic stere'i'ds intermixed 

 with sclereids, and the libriform shows the same peculiarity as in 

 the root. The leaf-structure is bifacial, and the midrib, from the 

 base of the blade to about the middle of this, is composed of a 

 stele , circular in cross-section , beside of an open arch-shaped mestome- 

 strand above this, close to the ventral epidermis; the center of the 

 stele is occupied by a typical pith; around the stele is a thick sheath 

 of stereome. This steloid structure in the midrib recurs in the petiole. 

 The Statement by Solereder that the midrib of Hamamelis shows 

 a structure distinct from that of Liquidambar is not correct, since 

 there is a stele in both; however Soloreder does not seem to have 

 examined other species than just Hamamelis japonica. 



Theo Holm. 



Holm, T., Medicinal plants of North America. 6 0. Helian- 

 themum Canadense L. C. Rieh. (Merck's Report. XXI. p. 38 — 41. 

 fig. 1-17. Febr. 1912.) 



The so-called frost-plant or frostwort, Heliayithemum Canadeiise, 

 was formely used in scrofulous diseases, diarrhea and secondary 

 Syphilis; it is called frostwort because in late autumn acicular ice- 

 crystals are thrown off from the base of the stems, where the bark 

 is cracked. The vegetative reproduetion is secured by overwintering 

 buds in the axils of the basal leaves, and by root-shoots which are 

 very abundant. It has two kind of fiowers, the normal or ephemeral, 

 with large ) T ellow petals and many-seeded capsules; and some that 

 are very small, cryptopetalous or apetalous, with a smaller number 

 of stamens and seeds. The root has a broad secondary cortex tra 



