ARTIFICIAL KEY TO THE NATURAL ORDERS. 
311 
225 Stems jointed 225* 
Stems not jointed 226 
225* Fructification in cones. ' The Horsetail Tr., Equisetacb^H, 561 
Fructification axillary and solitary. The Chara Tr., Charace^, 669 
226 Plants with distinct leaves 227 
Plants mere leafless expansions 230 
227 Fructification growing on the back of the leaves. The Fern Tr., FiLlCES, 562 
Fructification distinct from the leaves 228 
228 Seed-vessel sessile in the axils of leaves. The Clubmosa Tr., Lycopodiace^, 563 
Seed-vessel on stalks 229 
229 Seed-vessel with a lid and calyptra. The Moss Tr., Musci, 565 
Seed-vessel without lid and calyptra. The Jugermannia Tr., in IIepaticejg, 566 
230 Seed-vessel opening into valves. EicciecB Tr., in Hepatic^, 666 
Seed-vessel without valves 231 
231 Seed-vessel stalked and external. The Marchantia Tr., in HEPATlCiE, 566 
Seed-vessel stiilkless and usually internal 232 
232 Growing under water. The Sea-weed Tr., Alg-E, 670 
Growing in the air 233 
233 Fructification in external shields. The Lichen Tr., Lichenes, 567 
Fructification in internal cases. The Mushroom Tr., Fungi, 568 
COMPARATIVE VIEW OF THE TWO GREAT CLASSES IN THE NATURAL 
SYSTEM. 
DiCOLYTEDOXOUS PLANTS. 
Stems generally branched, and when 
old, covered with cracking bark. 
Wood, consisting of concentric circles; 
the central part the oldest and hardest; 
the bark connected with a central pith, by 
means of thin plates called medullary 
rays. 
Leaves with veins arranged in a netted 
manner; usually jointed with the stem. 
Flowers usually with the parts arranged 
in fours or fives. 
Embryo with two or more seed-lobes or 
cotyledons."* 
Found wild as trees all over the world, 
except in the very highest latitudes. 
MONOCOTYLEDONOUS PLANTS. 
Stems generally quite simple ; and when 
old, covered with smooth bark. 
Wood not consisting of concentric cir- 
cles; the central part the youngest and 
softest; the bark not connected with a 
central pith by means of medullary rays. 
Leaves with simple parallel veins, which 
are not netted; usually not jointed with 
the stem. 
Flowers usually with the parts arranged 
in threes. 
Embryo with only one seed- tube or 
cotyledon. 
Found toild as trees only in hot climates, 
and chiefly within the tropics. 
It will be useful to the student to examine by the Table all such 
plants as may be met with, whether known or not ; though it must be 
acknowledged that there are serious difficulties in finding the names of 
sti'ange plants by the Natural System, unless they manifestly belong to 
some prominent Natural family. That teachers and pupils may not be 
discouraged in their labors, it is well they should know there are diffi- 
culties in the science ; that learned Botanists are often obliged to refer 
to the common name, or tradition, in order to find where others have 
placed, and how named a particular plant. 
* The Sub-class, Gymoape.rms^ or seeds naked, includes the cone-hearing plants with eeveriil 
cotyledons, and therefore not well classed among Dicolytedonous plants, but agreeing with them in 
many particulars, they are conveniently placed here. The ovules have no pericarp, are sometimes 
protected by a mere scale. When the seed germinates, the several cotyledons appear as a tuft of 
•eed leaves around the rootlet. 
