NATURAL SYSTEM OE LINDLEY. 421 



Sexual or Flowering Plants. 



Wood of stem youngest in the centre, cotyledon single. 

 Leaves parallel-veined, permanent, wood of stem 



always confused III/Endogens. 



Leaves net-veined, deciduous, wood of stem, when 



perennial, arranged in a circle with a central pith IV. Diotyogens. 



Wood of stem youngest at the circumference, always 

 concentric, cotyledons two or more 



Seeds quite naked V. Gymnogens. 



Seeds enclosed in seed-vessels . . . VI. Exogens. 



The following are the sub-classes of Eadogens and Exogens adopted 

 by Lindley : — 



Sub-class 1. Glumaceous. — Floral envelopes imbricated. 

 2, Petaloid. — Floral envelopes verticillate. 



a. Unisexual, often achlamydeous., 



i. Hermaphi'odite, ovary inferior. 



c. Hermaphrodite, ovary superior. 



Exogens. 



Suh-class 1. Diclinous. — Flowers unisexual. 



, 2. Hypogynous. — Flowers usually hermaphrodite, stamens completely 



hypogynous, free from the calyx or corolla. 

 3. Perigynous. — Flowers usually hermaphrodite, stamens growing to 



the side of either the calyx or corolla ; ovary superior, or nearly so. 

 4. Epigynous. — Flowers usually hermaphrodite, stamens growing to the 



side of either the calyx or corolla ; ovary inferior or nearly so. 



Under the classes Lindley enumerates 303 natural orders, which are 

 grouped together under 56 alliances. In this system of Lindley the 

 divisions of Asexual and Sexual plants correspond to Endlicher's 2 

 Eegions ; the 7 classes represent Endlicher's 5 sections ; and the 56 

 alliances are equivalent to the 61 classes in Endlicher's system. 

 This division may be presented thus : — 



Classes. Wood. Leaves. En^igpgg, Sexes. Bmlsryo. 



1. Exogense . . Exogenous Netted 5 or 4-nary Perfect . Dicotyledonous. 



( Parallel 1 



2. Gymnospermse Exogenous < or > None . Seed naked Dicotyledonous. 



I forked 1 



3. Endogenffl . Bndogenpus Parallel Ternary Perfect . Monocotyledonous. 



4. Diotyogense . Endogenous Netted . Ternary Perfect . Monocotyledonous. 



(5. Acrogenffi . . Aorogenous | ^/^one ( ^™® ' ^™® ' " Acotyledonous. 

 6. Thallogenae . None . . . None . . None . None . . Acotyledonous. 



Henslow has given a comparative view of aU these systems, point- 

 ing out, in a tabular form, the corresponding divisions in each of 

 them : — 



