251 



Sub-Class II. ENDOGEN^, or MONOCOTY- 

 LEDONOUS PLANTS. 



MoNocoTYLEDONES, Juss. Gen. 21. (1789); Desf. Mem. Inst. 1.478. (171)6). — En- 

 dorhizeyE, Rich. Anal. (1808) — MoNocoTYi.EDONEiE or Endogen^, Dec. 



Thtorie, 209. (1813) CryptocoTyledone.e or Graniferje, Agardh Apli. 



73. (1821.) 



Essential Character Trunk usually cylindrical when a terminal bud only is 



developed, 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 addi- 

 tion 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 distinct, 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; rarfic/e usually enclosed within the substance of the embryo, through which it 

 bursts when germinating. 



Nothing can be more simple than the mode of distinguishing; Monocoty- 

 ledonous from Dicotyledonous plants, notwithstanding the difficulty of fixing 

 upon any single character of separation. It is true 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 

 lieaves of Monocotyledons 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 Orchidese ; the ternary division of the flower of Monocoty- 

 ledons is often departed 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 exists, as in the common Rush and in the Bamboo ; 

 and the conical branched character of Dicotyledons is assumed in Grasses 

 and Asphodeleee. 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 shew them to be at once of the latter struc- 

 ture ; so in Juncus, in which pith is present, no other character is at variance 

 with those of Monocotyledons ; and again in Orchidea;, in which a com- 

 plete 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 considered as the natural struc- 

 ture of this primary division ; seeds without albumen occurring only in 

 certain genera of the paradoxical Aroideee, and in some other Monocoty- 

 ledonous orders which are chiefly aquatic. It is a fact well deserving atten- 

 tion, that Monocotyledons differ from Dicotyledons in their geographical 

 distribution as well as in structure ; a remarkable proof of the hypothesis, 

 that the forms of vegetation are controlled by peculiarities of climate,- acting 

 in an unknown manner. From the enquiries of Humboldt, it appears that 

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



