150 Neilgherry Plants. 



their wood. Descending still lower in the scale we come to two 

 groups of cellular plants, the Rhyzanths, mushroom-like plants, and 

 the Podostemons, sea-weed-like plants, agreeing with Algae in almost 

 every thing except their fructification. 



The leaves of Dicotyledons are usually attached to, and separate 

 from, the stem by an articulation, and are reticulated, that is, their 

 veins anastomose and form a network ; but this is not quite absolute, 

 as it is wanting in the leaves of most of the Gymnosperms. 



The flowers are for the most part quinary in the number of their 

 parts, and are generally furnished with both clayx and corolla ; but 

 departures from both these rules are frequent : most of the Homo- 

 gens have ternary, and many families quaternary flowers, while num- 

 bers have no corolla. 



The seed is usually enclosed in a pericarp, but here also a striking 

 exception occurs, the whole of the coniferus family, forming Lindley's 

 Gymnosperms, having naked ovules and seed, a privation combined 

 with some interesting peculiarities of the anatomical structure of the 

 whole plant. The seed itself is either perfect or imperfect, that is, 

 is furnished with an embryo having two or more opposite cotyledons, 

 or is sporulose : imperfectly developed as in Rhyzanths. The em- 

 bryo also is perfect or imperfect, with or without albumen. The al- 

 buminous ones are intra or extra albuminous, enclosed within the 

 albumen like the yoke within the white of an egg, or placed on the 

 outside of it, as in the case of the curvembryate orders. 



From this description, brief and imperfect as it is, we find there 

 are five modifications of structure, as regards vegetation, forming so 

 many distinct groups. 1st Exogens, as generally understood with the 

 wood in zones or concentric circles : 2d Homogens, first associated 

 as a distinct group by Dr. Lindley : 3d Gymnogens or Coniferae : 4th 

 Rhyzanths, having more the structure of Fungi than perfect plants ; 

 and 5th Podostemons, which seem to have an anatomical structure, 

 nearly allied to Algae, but which Mr. Griffith has determined, from 

 actual dissection of the seed, to be dicotyledonous. Then as regards 

 the structure of the seed there are exalbuminous and two modifica- 

 tions of albuminous embryos ; and a fourth where it is imperfect. 

 The albumen, moreover, greatly varies in quantity, being sometimes 

 very abundant with a minute embryo, varying thence to a large 

 embryo and very sparing albumen. 



All these variations are available for the purposes of classification, 

 and doubtless when thoroughly investigated, with special reference to 



