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BOTANY. 497 
Embryo | dicotyle- Class, an adjective form, without such prolongation. Thus 
onous; e growt Q ae 
aucine | exogenous MOG the genus Rosa gives name to a particular tribe, 
DAT iass Rosee, of the order Rosacee ; the genus Malva to 
pericaroNs ar tu yon once the tribe Malvee of the order Malvacee, &c. 
1 yiedonous ; e . lig : ‘s 2 
furnished 4 | erowth endogen- The number of genera in an order is quite as inde 
with ous . . . ENDOGENS. finite as that of orders in a class, or other great di- 
aomens duci UE Meee Gymwosrerms, | Vision. While some orders are constituted of a single 
a a S b cs . 
a Pee genus, as Equisetaces, Grossulacee, &c. (just as 
oe hearer spores instead of many genera contain but a single known species), 
5 ag ce ds ie erase nok: SOROS others comprise a large number; nearly nine hundred 
a but with regular stems, gowing being embraced in the last general enumeration of 
a i from the apex, andtfurnished | the Composite. The names of genera are Latin 
Ne eee ia ame SR, aon tat te EERE substantives, in the singular number, and mostly of 
| flowers, | and with no distinction of stem Greek or Latin derivation. Those which were 
| and leaves, or regular axis of 7 we known to the ancients, generally preserve their class- 
L ( growth. . . . . . . + + THALLOGENS. | joa] appellations (Ex. Fagus, Prunus, Myrtus, Viola, 
These six classes are very unequal, in respect to 
_ the number of plants they embrace: the Exogenous 
class containing many more species as well as orders 
than all the other Flowering plants put together ; 
the Endogens also comprising numerous types; but 
the others very few in comparison. Convenience of 
analysis therefore requires that the larger classes 
should be broken up into subclasses, alliances, co- 
horts, or by whatever name groups intermediate be- 
tween the classes and orders may be termed; and 
| the accomplishment of this object, so as to form na- 
tural groups, is at present the great desideratum in 
systematic botany. But until this be done, we are 
obliged to use artificial analyses of the classes, or to 
throw the orders into groups which, in proportion as 
they are rendered natural, it becomes impossible 
strictly to cireumscribe. In this view the great 
class of Exogenous plants is usually broken up into 
three very convenient, but nearly artificial divisions, 
sometimes called subclasses; founded on the pre- 
sence, absence, or union of the petals, viz., 
1. PotypeTaLz, the Polypetalous Exogens ; 
where the calyx and corolla are both pre- 
sent, and the latter composed of distinct 
petals. 
2. MonoreTALa, the Monopetalous Exogens, 
where the petals are united. 
3. APETALZ, the Apetalous Exogens, where the 
petals are wanting ; and the floral envelopes, 
if present at all, consist of the calyx alone. 
These divisions, as well as the other classes, are 
subdivided by different authors in various ways, 
which need not be specified; since it is only the 
classes and the orders that are considered to rest 
upon a stable basis. 
The orders, or families, are to be viewed rather 
as natural groups of genera, than as subdivisions of 
the classes. Their names, which are always plural, 
sometimes express a characteristic feature of the 
group ; as, for instance, Leguminosae, or the Legum- 
inous plants, such as the pea, bean, &c., whose fruit 
is a legume; Unmbellifere, or Umbelliferous plants, 
so named from having the flowers in umbels; Com- 
posite, an order having what were termed compound 
flowers by the earlier botanists; ZLabiate, so called 
from the labiate or two-lipped corolla which nearly 
all the species exhibit ; Crucifere, which have their 
four petals disposed somewhat in the form of a cross, 
&c. But more frequently, and indeed as a general 
rule, the name is formed from that of some leading 
or well-known genus, which is prolonged into the 
adjective termination acee. Thus, the plants of the 
order which comprises the mallow (Malva), are 
called Malvacee ; that is, Plante-malvacee, or in 
English, Malvaceous plants; those of which the 
Rose (Rosa) is the well-known representative, are 
Rosacea, or Rosaceous plants, &e. . This termina- 
tion in aceeé being reserved for orders, should not be 
applied to sub-orders or tribes; which usually bear 
I. 
the name of their principal or best-known genus, in 
L 
&e.); and even the barbarous or vulgar names of 
plants are often adopted, when susceptible of a Latin 
termination, and not too uncouth; for example, Thea 
and Coffea, for the Tea and Coffee plants, Bambusa 
for the Bamboo, Yucca, Negunda, &c. But more 
commonly generic names are formed to express some 
botanical character, habit, or obvious peculiarity of 
the plants they designate; such as Arenaria, for a 
plant which grows in sandy places, Dentaria, for a 
plant with toothed roots, Lunaria, for one with 
moon-shaped pods, Sanguinaria, for the Blood-root, 
Crassula, for some plants with remarkably thick 
leaves. These are instances of Latin derivatives; 
but recourse is more commonly had to the Greek 
language, especially for generic names composed of 
two words, such as Menispermum or Moon-seed ; 
Lithospermum, for a plant with stony seeds; Melan- 
thium, for a genus whose flowers turn of a black or 
dusky colour; Hpidendrum, for Orchideous plants 
which grow upon trees; Liriodendron, for a tree 
which bears lily-shaped flowers, &c. Genera are 
also dedicated to distinguished persons, a practice 
commenced by the ancients; asin the case of Peonia, 
which bears the name Peon, who is said to have 
employed the plant in medicine; and of Adonis, for 
the plant which is fabled to have arisen from the 
blood of the wounded Adonis; and Euphorbia, Ar- 
temisia, and Asclepias, are also examples of the kind. 
Modern names of this kind are given in commemora- 
tion of botanists, or of persons who have contributed 
to the advancement of natural history. Magnolia, 
Bignonia, Lobelia, and Lonicera, dedicated to Mag- 
nol, Bignon, Lobel, and Lonicer, are early instances 
of the practice; Linnea, Tournefortia, Jussicza, 
Gronovia, &c., bear the names of more celebrated 
botanists; and at the present day almost every de- 
votee or patron of the science is thus commemorated. 
The names of species, as a general rule, are adjec- 
tives, written after those of the genera, and established 
on similar principles; as Magnolia grandiflora, the 
Large-flowered magnolia; MZ. macrophylla, the Large- 
leaved magnolia; Bignonia radicans, the Rooting- 
bignonia, &e. The generic and specific names, taken 
together, constitute the proper scientific appellation 
of the plant. Specific names sometimes distinguish 
the country which a plant inhabits (Ex. Viola Cana- 
densis, the Canadian violet), or the station where it 
naturally grows (as V. palustris, which grows in 
swamps, V. arvensis, im fields, &e.), or they express 
some obvious character of the species; as V. rostra- 
ta, where the corolla bears a remarkably long spur ; 
V. tricolor, which has three-coloured flowers; V. 
rotundifolia, with rounded leaves; V. lanceolata, 
with lanceolate leaves; V. pedata, with pedately 
parted leaves; V. primulefolia, where the leaves 
are compared to those of the Primrose; V. asarifo- 
lia, where they are likened to those of Asarum; V, 
pubescens, which is hairy throughout, &c. Fre- 
quently the species bears the name of its discoverer 
or describer, when it takes the genitive form, as 
Viola Muhlenbergiti, V. Nuttallii, &e. When such 
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