NATURAL ORDERS. lxxv 
VY. ARRANGEMENT OF THE NATURAL ORDERS IN THE, 
PRESENT WORK. 
The very unequal manner in which the several Natural Orders are 
represented in the British Isles renders it impossible, in a work con- 
fined to British Plants, to give any fair idea of the subclasses into which 
these Orders have been grouped, or of the principles which have guided 
the authors of the linear arrangement the most generally followed. The 
following recapitulation is therefore merely intended as a sort of table 
of contents, showing the order in which the families follow each other 
in the present work; at the same time that the attention is called to 
one or two of the most striking, the most important, or the easiest ob- 
served features of each one. These characters are, however, general, 
not always without exception, and sometimes specially applicable to 
British genera only. 
CLASS I,—DICOTYLEDONS. 
In the germination of the seed the plumula arises between two (rarely 
more) lobes or cotyledons of the embryo, or from a terminal notch. [The 
vascular tissue of the stem forms a ring or rings between the bark 
and pith. The nerves of the leaf are branched and netted (see also 
Arum, Tamus and Paris in Monocotyledons). The parts of the flower 
are usually in fours or fives.] 
Subclass 1. THALAMIFLOR®.—Petals distinct from the calyx, and 
from each other, seldom wanting. Stamens usually hypogynous, or 
nearly so. [LHxceptions.—The calyx or corolla is absent in some Ranun- 
culaceze, Cruciferz, Violacez, Caryophyllacez. The petals cohere more 
or less in some Fumariacezx, Polygalacez, Portulacee, Tamariscinee, 
Malvacez. The stamens are epigynous or perigynous in Nympheacezx 
and some Caryophyllacez. ] 
* Ovary apocarpous. 
I. Ranunculacese. Petals defin'te. Stamens indefinite. 
II. Berberidez. Perianth and stamens in twos or threes, or their 
multiples. Anthers opening by recurved valves. 
IIJ. Nymphzacez. Aquatic plants with indefinite petals and sta- 
mens, the inner petals passing gradually into the outer stamens. 
** Ovary syncarpous. Placentas parietal (except in Polygalacez). 
IV. Papaveracee. Perianth regular, in twos or fours. Stamens in- 
definite. 
VY. Fumariacez. Perianth very irregular, in twos or fours. Stamens 
6, in two sets. 
Vi. Cruciferz. Sepals and petals 4 each. Stamens 6, of which 2 
shorter. 
VII. Resedacez. Petals small, unequal, some divided. Stamens few 
but indefinite. Capsule open at the top before it is ripe. 
VIII. Cistaceze. Sepals 3, equal, or with additional small ones. Petals 
5, regular. Stamens indefinite. 
TX. Violaceze. Stamens 5; the anthers on the inner face of very 
short broad filaments, usually united inaring. Capsule 3-valved. 
