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Sub Class II. ENDOGENiE, or MONOCOTYLEDONOUS 



PLANTS. 



Monocotyledones, Juss. Gen. 21. (1789); Desf. Mem. List. 1. 478. (1796).— Endobhizej;, 

 Rich. Anal. (1808). — Monocotyledon-eve or Endogen«, Dec. Theorie, 209. (1813). — 

 Cryptocotyledone.e or Granifeeje, Agardh Aph. 73. (1821.) 



Essential Character. — Trunk usually cylindrical when a terminal bud only is deve- 

 loped, becoming- conical and branched when several develope ; consisting - of cellular tissue, 

 among - which the vascular tissue is mixed in bundles, without any distinction of bark, wood, 

 and pith, and destitute of medullary rays ; increasing in diameter by the addition of new 

 matter to the centre. Leaves frequently sheathing at the base, and not readily separating - from 

 the stem by an articulation, mostly alternate, with parallel simple veins, connected by smaller 

 transverse ones. Flowers usually having a ternary division ; the calyx and corolla either dis- 

 tinct, or undistinguishable in colour and size, or absent. Embryo with but 1 cotyledon; if 

 with 2, then the accessory one is imperfect and alternate with the other ; radicle usually en- 

 closed within the substance of the embryo, through which it bursts when germinating. 



Nothing can be more simple than the mode of distinguishing Monocotyledon 

 nous from Dicotyledonous plants, notwithstanding the difficulty of fixing upon 

 any single character of separation. It is .rue that the structure of the stem is 

 not sufficient, because it is frequently impossible, in annual plants, to ascertain 

 if it be Exogenous or Endogenous ; the parallel veins of the leaves of Mono- 

 cotyledons are not always constant, because some genera have reticulated 

 ones ; the want of articulation between the stem and the leaves, although very 

 prevalent in Monocotyledons, sometimes changes to perfect articulation, as in 

 OrchideaB ; the ternary division of the flower of Monocotyledons is often de- 

 parted from, as in Aroidese and the neighbouring orders ; many Dicotyledons 

 have also ternary floral envelopes ; Monocotyledons have sometimes more than 

 one cotyledon, as the common Wheat ; finally, when the stem is capable of 

 being strictly examined, a distinction between wood and pith occasionally ex- 

 ists, as in the common Rush and in the Bamboo ; and the conical branched 

 character of Dicotyledons is assumed in Grasses and Asphodeleae. Hence it 

 is by a combination of characters that the two great divisions are to be known, 

 and not by any absolute single mark : for instance, in Grasses, in which the 

 stem is, as an eminent botanist has justly remarked, less Endogenous than in 

 almost any other Monocotyledons, the leaves, flowers, and seeds, well show 

 them to be at once of the latter structure ; so in Juncus, in which pith is pre- 

 sent, no other character is at variance with those of Monocotyledons ; and 

 again in Orchidea?, in which a complete disarticulation of the stem and leaves 

 takes place, every other point of structure is that of Monocotyledons. Mr. 

 Brown has remarked {Congo, 481), that the presence of albumen may be con- 

 sidered as the natural structure of this primary division ; seeds without albu- 

 men occurring only in certain genera of the paradoxical Aroide*, and in some 

 other Monocotyledonous orders which are chiefly aquatic. It is a fact well 

 deserving attention, that Monocotyledons differ from Dicotyledons in their geo- 

 graphical distribution as well as in structure ; a remarkable proof of the hypo- 

 thesis, that the forms of vegetation are controlled by pecubarities of climate, 

 acting in an unknown manner. From the inquiries of Humboldt, it appears 

 that Monocotyledons form, in equinoctial regions, about l-6th of the flowering 

 plants ; in the temperate zone, between 36° and 52° latitude, l-4th ; and 

 towards the polar circle, nearly l-3d. 



The most important substance that they produce is amylaceous matter, 

 which exists in great quantity in some of them, which hence become of incal- 



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