KNDOQKNS. 



ENDOOENS. 



ItuporUnt M the character furniahed by the internal manner of 

 growth of an Endogen obviously in, it ia much enhanced in value by 

 iU bong found very generally accompanied by peculiarities of organi- 

 sation in other parts. The leaves hare in almost all cases the reina 

 placed in parallel lines, merely connected by transverse single or 

 nearly aingle ban. Straight-veined foliage ia therefore an external 

 aymptom of an endogenoua mode of growth, When auch an appear- 

 ance i* found in Exogena it ia always fallacious, and ia found to be 

 owing to the excessive ai*e and peculiar direction of a few of the 

 larger veiua, and not to be a general character of all the venous 

 system ; M ia aufflciently obvioua in Plmtago lanccotata, Gentian* 

 Infra, and many more. 



The flowers too of Endogena have in moat cases their sepals, petals, 

 and atamens corresponding with the number three, or clearly refer- 

 rible to that type ; and the pistil usually participates in the same 

 peculiarity. Where auch a proportion exists in Exogens it is usually 

 confined to the aepala and petals by themselves, or to the pistil by 

 itself, not extending to the other organs. In Endogena it U almost 

 univenal in all the whorla of the flower, although sometimes obscured 

 by the abortion, dislocation, or cohesion of particular parts, as happens 

 in the whole of the extensive natural order of grasses. 



and a plumule from a little above the radicle ; in other cases its 

 I embryo has a slit on one aide, in the cavity of which the plumule 

 reposes, or, finally, the embryo is a flat plate as in Onuses, with the 

 plumule and radicle attached to its face near the base. In the latter 

 case the flat plate is a solitary cotyledon, which in the second instance 

 ia folded together to aa to give the embryo the appearance of being 

 slit, and, which in the first or moat habitual condition ia not only 

 folded up but united at its edges into a case, entirely burying the 

 plumule and cotyledon. Hence the embryo of an Endogen is called 

 Monocotyledonous ; a name that is really unexceptionable, notwith- 

 standing the occasional appearance of a second rudimentary cotyledon, 

 as occurs in common wheat. 



It baa already been stated that the radicle ia protruded in germina- 

 tion from within the substance of the embryo ; the base of the radicle 

 is consequently surrounded by a minute collar formed of the edges of 

 the aperture produced by the radicle upon its egress. For this reason 

 Exogens are called endorhiral. 



Hence the great natural class of plants forming the subject of these 

 remarks has five most important physiological peculiarities, by all 

 which combined, or usually by each of which separately, the class 

 may be characterised : 



Endogenous VrgeUtion. 



of Cbnw capiiala (a) ; tftxiftria tottiftr* () ; Iriarlra rrnlrifaia (/). Pmdcmacrm, represented by fatidanvi odoratiuimut (r) ; 

 il~ir'-r, bT H<ua Saftmlmm (d) ; (iramixartf, by Bamlnaa anmdimHxa () ; and Arborcxxnt Amaryllidacnr, by Agavr Americana (?). The fore and back 

 froondi arc composed of mall palm*, rnm, rtubo, and llllw*oiu plant*. 



1. The wood is endogenous. 



2. The leaves are straight-veined. 



3. The organs of fructification are ternary. 



4. The embryo is monocotyledonous. 



5. The germination ia endorhizal. 



This explains why Endogena are also called Monocotyledons and 

 Endorhiza ; they have moreover been called Cryptocotyltdontcc by 

 Agardh, Acroblatta by Reichenbach, and OaviojiTtylce by the school of 

 Oken. 



It may however be readily supposed that, viewed as a large class of 

 plants, Endogens are essentially characterised only by the combination 

 of these five peculiarities, and that occasional deviations may occur 



The effect of the manner of growth In Endogena ia to give them a 

 very peculiar appearance. Their trunks frequently resemble columns 

 rising majestically with a plume of leaves upon their summit; and 

 the leave*, often very large the fan shaped leaves of some palms 

 are from 20 to 80 feet wide have moat commonly a lengthened 

 form, resembling a sword-blade if stiff, or a strap if weak and broad. 

 A landscape consisting entirely of Endogens would have such an 

 appearance as U presented by the cut in this page. 



Them peculiarities are connected with others belonging to endo- 

 genous vegetation in its moat rudimentary condition. The embryo of 

 an Endogen is in its commonest state a small undivided cylinder, 

 which protrudes from within its substance a radicle from one end 



