257 



f- 



Hemarlcs 07i Dooknia and Eykia, two new genera of Screw Pines, pre- 

 ceded by some general ohservations u;pon that class of plants ; heing the 

 substance of a Lecture, delivered on the 21th May, 1854, before the 

 Royal Academy of Sciences at Amsterdam ; by Dk. W. H. De Vkiesb, 

 Member of the Academy. 



There are some families of plants, which, on account of their form, 

 aspect, and locality, particularly engage the attention, not of botanists 

 alone, but of every observer of nature. They are called Physiognomic 

 Plants. What we know of the diffusion, of plants over the surface of 

 the earth, teaches us to understand not only that intimate connection 

 existing between the plants and the soil, but also that existing between 

 the plants and all other external circumstances, and makes us recognize 

 this connection as the first and cluef cause of their distribution. Do 

 we need examples ? I invite your attention only to the appearances of 

 vegetation in our own countiy (Europe);— to our almost boundless 

 tracts overgrown with Calluna mdgaris ; to our Pens, covered with 

 Sphagna ; to the Pine-woods, in which here a Moss-vegetation, in an- 

 other place Vaccinium Myrtillus, or in another, the Eagle-fern, Fteris 

 aquilina, often develope themselves in gigantic forms ; and all these in 

 their peculiar localities, and in such number, that they constitute emi- 

 nently the chief character or form of plant. In the more northerly re- 

 gions may be seen the Cenomyce rangiferina, or Reindeer Moss, whicli 

 covers the soil for many square miles ; or the dwarf Birch, Betula nana, 

 a sort of tree which scarcely attains a ftw inches in height, but clusters 

 in mjTiads over a small space. These plants give us a just idea of 



what we call social growth. 



The countries lying between the tropics, present the most physiog- 

 nomic forms of statelier development. The Palm form is found prin- 

 cipaUy in Mexico and South America. The East Indian Archipelago, 

 Java and the Philippine Islands are richest in Ferns, and chiefly in 

 Tree-ferns. The Bldzophora affect the neighbourhood of the mouth 

 of great rivers : they may be caUed, for distinction, eminently coast- 

 plants. They are generally found where great rivers are discharged 

 into still bays or coves of the sea. where there is but little surge. They 

 are pretty shrubs (says Junghuhn). attaining a height of ten to twenty- 

 five feet, and of such peculiar aspect, that no other mstances arc found 

 in the vegetable kingdom . The stem does rise din ct from the earth, but 



VOL. VI. 



