130 Anatomie. — Biologie. 



Zealand Piperaceae. (Trans, and Proc. of the New Zealand 

 Institute. \^ol. XLIV. p. 339 348. With 17 figures in the text. 1911.) 



A Short description is given of the appearance and habit of 

 Macropiper excelsum and Peperomia Endlicheri, two of the three 

 New Zealand representatives of the Piperaceae. 



The author gives an account of the woody stem structure of 

 ;]/. excelsum, its'most obvious feature is the double bündle ring, 

 which is characteristic of the woody Piperaceae. The base of the 

 stem is swollen and is stored with nutritive material, chiefly starch; 

 the roots are adventitious, for the primary root is very early lost. 

 Secondary thickening occurs to a marked extent. 



P. Endlicheri is usually a rock plant, its stem is succulent and 

 its leaves störe water. A very short description is given of the 

 structure of the stem and petiole; the adventitious roots form 

 mat-like masses at the nodes and in them wood is only feebly 

 developed. 



Some details of the transition phenomena of the seedling ot 

 Macropiper excelsum are given. The author concludes thati/«C7'0/)//)6'r 

 is a primitive form while Peperomia is reduced, that monocotyle- 

 dons "may have arisen as modifications and reductions of the 

 dicotyledonous type, as more specialised forms, though earlier in 

 time, perhaps, than the Piperaceae:' E. de Fraine. 



Gpoom. P., Remarks on the Ecology of the Coniferae. 

 Ann. of Botany XXIV. p. 244-269. 1910.) 

 The cause of the xeromorphic foliage and tracheidal wood in 

 Coniterae, their survival in competition Avith dicotylous trees. and 

 the suppression of many coniferous forms in the past are the main 

 questions dealt with. Discussion is limited to the north-temperate 

 forms since their phvsiology is better known. In discussing general 

 features of distribulion, Schimper's view. that the evergreen 

 nature of Coniferae is combined with a slow rate of transpiration 

 during a physiologically dry season , is shown to be incomplete 

 since ''the Coniferae have a wide ränge of distribution including 

 occurrence in the evergreen tropical humid region, and even in 

 oertain cold-temperate regions they demand a relatively humid 

 habitat. The proposition that the coniferous mechanism does not 

 necessarily involve a slow rate of transpiration per unit of surface 

 of leaf i.s' introduced by a critical examination of von Höhnel's 

 results. The author gives a table of dimensions of coniferous leaves 

 prepared from bis own measurements; the possibility of considerable 

 Variation in the same species is emphasized, but Larix is shown 

 to have rapidlv transpiring leaves. Experiments also showed that 

 the transpiration current in'the coniferous stem may be rapid under 

 ronditions favourably to a maximum result, but liable to conside- 

 rable Variation. The figures tabulated show that Larix may be 

 equal to dicotvlous trees. The problem why Coniferae have preserved 

 the tracheidal" structure of the wood is also dealt with. The measure- 

 ments of tracheae for a number of species of Quercus show that 

 16 species with the widest tracheae are deciduous, while 9 species 

 with narrow tracheae are evergreen. In discus.sing xerophytism ot 

 the Coniferae it is indicated that even with their xeromorphic leaves, 

 raany species succumb from desiccation or grow feebly in places 

 where ordinarv dicotylous trees survive. 



