upon the Distribution of Vegetables. 181 



LIMESTONE. ARGILLACEOUS SCHIST. 



Luzula glabrata, Desv. Luzula spadicea, DC. 



Juncus monanthos, Jacq. Juncus trifidus, L. 



Primula pubescens, Jacq. Primula hirsuta, Willd. 



Phyteuma orbiculare, L. Phyteuma fistulosum, fib. 



Lepidium alpinum, L. Lepidium brevicaule, Hoppe. 



Anemone grandiflora, Hoppe. Anemone alpina, L. 



Ribes alpinum, L. Ribes petraum, Wulf. 



Gentiana bavarica, L. Gentiana imbricata, Frcehl. 



Dianthus alpinus, L. Dianthus glacialis, Haencke. 



We also sometimes see species acting, upon one formation, 

 the part that analogous species perform upon others ; so that 

 under different latitudes, genera and even species reciprocally 

 replace each other. 



LIMESTONE. ARGILLACEOUS SCHIST. 



Sesleria ccerulea Sesleria disticha 



Luzula maxima Luzula spicata 



Carex mucronata Carex frigida 



Chrysanthemum atratum Chrysanthemum alpinum 



Erigeron alpinum Erigeron uniflorum 



Arnica scorpioides Arnica Doronicum 



Phyteuma orbiculare Phyteuma hemisphcericum 



Campanula alpina Campanula thyrsoidea 



Rhododendron hirsutum Rhododendron ferrugineum 



Saxifraga aphylla Saxifraga muscoides 



Astragalus glycyphyllos Phaca astragalina 



Biscutella laevigata Erysimum lanceolatum 



The altitudinal limits of vegetation in this country are as 

 follow. The walnut rises to 2700 feet ; the cereal plants, 

 sometimes as high as 3764 feet ; the beech to 4000, and in a 

 stunted state as high as 4800 ; the fir to 5200. The region 

 of alpine shrubs is between 5000 and 7000 feet ; these are, 

 the two species of Rhododendron, the Betula viridis, and the 

 small willows. Pinus pumilio is still vigorous at 5903. We 

 will not follow the author in the comparisons which he esta- 

 blishes between these heights, and those observed by Zahl- 

 bruckner in lower Austria; Hegetschweller, Leopold de Buch 

 and General de Welden in Switzerland and Piedmont ; trees 

 and cultivated fields rise higher in these latter countries, as it 

 was easy to foresee in considering the difference of latitude. 

 In the Tyrol we observe also that certain specific forms of the 

 plain are modified by ascending to a greater height, to such 

 a degree as to have been taken by some authors for new spe- 

 cies. Such are, Poly gala alpestris, Rb. Biscutella alpestris, 

 Kit., Rhinanthus alpestris, Wahl., Chrysanthemum atratum^ 

 Jacq., Euphrasia minima, Schleicher, Juniperus nana, Will., 

 and many others. All are distinguished from their primitive 

 form, by being less high, and by having corollas relatively 

 larger, more simple leaves, and fewer ramifications. 



