7^^ n J 
TEXTS AND COMMENTS. 
three-quarters of the vegetable creation of our epoch, and which appear to date their predominance 
from the origin of the tertiary formations. The plants even extend hack to the commencement of the 
cretaceous period. Thus we may distinguish in the reign of Angiosperms two great periods, the 
cretaceous and the tertiary. 1. The Cretaceous formation, taken as a whole, appears to constitute a first 
period of the reign of the Angiosperms, forming the transition between the vegetation of the secondary 
formations and that of the tertiaries, — presenting, like the former, still a few Cycadaceje ; like the latter 
already a few angiospermous dicotyledons. This period is, moreover, characterised by several Coni- 
feras peculiar to it : in the marine subcretaceous lignites of the Isle of Aix, by marine plants and 
Conifera ; in the green sand of the South of England, by Cycadere, Coniferte, or marine plants only ; 
in the ferruginous sands of France, by an arborescent Fern ; in the fucoid sands solely by marine 
plants. These fucoid sands, which form a very distinct epoch, appear up to the present time charac- 
terised solely by marine vegetation, and in a botanical point of view constitute the line of demarcation 
between the cretaceous and the tertiary formations. 2. The collective nature of the plants of the 
Tertiary period, contemporaneous with all the tertiary deposits, and surviving even yet in the vegetation 
clothing the present surface of the earth, is one of the most characteristic. The abundance of 
angiospermous dicotyledons ; of monocotyledons of various families, but especially of palms, during at 
least a portion of this period, distinguishes it at once from the more ancient. In the cretaceous period, 
the angiosperms appeared almost to equal the gymnosperms ; in the tertiary they much exceed them. 
The division of this period into three principal epochs — eocene, mioeene, and pliocene, is sufficient for 
the comparison of the successive changes of the vegetable kingdom. The most remarkable characters 
drawn from the vegetable forms during these epochs appear to be — 1, or Eocene; the presence but 
rarity of Palms, confined to a small number of species ; the predominance of Algte and marine mono- 
cotyledons, attributable to the great extent of marine formations during this epoch. 2, or Miocene ; 
the abundance of palms in the majority of localities ; the existence of a tolerably large number of non- 
European ferns ; and particularly of the genus Steinhauera, supposed to be a rubiaceous plant. 3, or 
Pliocene ; the great predominance and the variety of dicotyledons, the rarity of monocotyledons, and 
especially the absence of palms ; lastly, the general analogy of the forms of these plants with those of 
the temperate regions of Europe, North America, and Japan. 
Finally, to conclude our observations on this flora of the last geological period, preceding the 
existing one, we will direct attention to the fact, that, in spite of the general analogies which exist, 
between the plants of these formations and those which at present live in the temperate regions, not 
one species appears to be identical at least with any plant now growing in Europe ; and if in some rare 
cases identities appear to exist, it is between these fossil plants and American species. Thus the flora 
of Europe, even in the most recent geological epoch, was very different from the existing European flora. 
TEXTS ANT) COMMENTS. 
PLANT GROWING. — " Can a collection of the finer kinds of greenhouse plants be grown to per- 
fection without some of them requiring, at certain times, more than ordinary greenhouse tem- 
perature ?" This question is frequently asked, but has never, to our knowledge, been properly answered. 
In reply we would remark, that the plants associated together in our greenhouses come from very 
varied localities, some from countries where frost is not known, and others from places where they 
are exposed to a lower temperature than is considered proper for them in this country. Hence, for 
example, though the heaths from the Cape may not be injured by a few degrees of frost, it is quite 
certain that the Kalosanths, or Crassnlas, as they are more commonly called, would suffer irreparable 
injury. Some plants from New South "Wales and New Holland are nearly hardy, but others ore 
remarkably tender, and require here something more than greenhouse temperature. Those persons 
who are the most successful exhibitors, grow many of what are considered greenhouse plants in 
considerable heat, and almost all the finer kinds of New Holland plants, require in the growing season 
a temperature above, rather than below, fifty degrees. It has frequently been explained in this 
Maya-hie that such plants as Crowea saligna, and elliptica, Eriostemons, Boronias; Chorozemas 
— Henchmanni, triangularis, and spectabile ; Gompholobiums — more especially splendens, versicolor, 
and polymorphum splendens; Podolobiums — staurophyllum, and triangulare, Pimeleas — more 
especially rosea, and Hendcrsonii ; Aphelexcs, Dillwynias, Burtonias, Polygalas, Leschenaultias, 
Acrophyllums — all these plants in their native habitats are exposed not only to warmer, but 
to longer summers than they are subject to in this country ; and hence, to grow them successfully, they 
must have more heat than they get in ordinary greenhouses. Indian Azaleas live and grow in a low 
temperature, and are not materially injured by a few degrees of frost, but they delight in a brisk 
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