482 ILLUSTRATIONS OF THE NATURAL ORDERS. 



Class II. Endogenous on Monocotyledonous Plants. 



Stem not distinguishable into bark, pith, .and wood ; but the latter 

 consisting of bundles of fibres and vessels irregularly imbeded in 

 cellular tissue ; the rind firmly adherent ; no medullary rays, and 

 no appearance of concentric layers : increase in diameter effected 

 by the deposition of new fibrous bundles, which at their commence- 

 ment occupy the central part of the stem. Leaves seldom falling 

 off by an articulation, sheathing at the base, usually alternate, entire, 

 and with simple parallel veins (nerved). Floral envelopes when 

 present mostly in threes, never in fives ; the calyx and corolla most 

 commonly undistinguishable in texture and appearance. Embryo 

 with a single cotyledon ; or, if the second is present, it is much 

 smaller than the other, and alternate with it. 



Conspectus of the Orders. 



S! roup 1. Flowers on a spadix, furnished with a double and free perianth 

 (answering to calyx and corolla). Ovary one- to thrcc-ecllcil, with a single 

 ovule in cacli cell. Embryo in hard albumen. — Trees with unbranched 

 columnar trunks. Palmje. 



Group 2. Flowers on a spadix ; with the perianth simple and free, or reduced 

 to a few scales, or commonly altogether wanting. — Chiefly herbs. 



Terrestrial. Fruit nut-like, or comose, one-seeded. Typiiace^s. 



Terrestrial, mostly with a spathc. Fruit baccate. Akacea:. 

 Aquatic (floating or immersed). 



Flowers developed from the edge of tho floating frond. Lemnace,*:. 



Flowers axillary or on a spadix. Naiad AC EiE. 



Group 3. Flowers not spadiceous, furnished with a double and free perianth 

 (calyx and corolla). Ovaries several, distinct, or sometimes united. Aquat- 

 ic herbs. Alismaceje. 



Gioup 4. Flowers with a simple or double perianth, which is adherent to tho 

 ovary, regular, developed from a spathc, polygamous or diclinous. Ovary 

 one-celled with parietal placental, or 3 - 9-cclled. Seeds destitute of albu. 

 men. — Aquatics. IIydrociiaridace.e. 



Group 5. Flowers pcifect with the double or 6-merous perianth adherent to tho 

 ovary (or more or less free in some Hamuxloroccoo and Biomeliaccaj). 

 Seeds with albumen, except perhaps the very minute ones of Orchidaccai, 

 &c. Leaves parallcl-vcined. 



