THE BOTANY OF THE FARM 431 



2. Hypogyncv in which the Perianth is free, the 



ovary is superior, and each flower has usually 

 stamens and pistil. 



3. Incomplete^ flowers incomplete, often staminate 



and pistillate, with no proper Perianth, or with 

 a few verticillate scales. 



Sub-class III. GLUMIFEILE flowers glymaceous, consisting 

 of imbricated bracts, venation parallel. 



CLASS III. ACOTYLEDONES, or ACROGEN^E, and THALLOGEN^E, 

 or THALLOPHYTA and ACROBRYA, in which the 

 plants are either entirely cellular, or consist partly of sca- 

 lariforrn vessels ; the stem when woody is acrogenous ; sto- 

 mata occur in the higher orders ; the leaves are either vein- 

 less or have a forked venation ; no flowers are present ; the 

 reproductive organs consist of Antheridia and Archegonia ; 

 spores or cellular embryos are produced which have no 

 cotyledons. Under this class there are two divisions : 

 Sub-class I. ACROGEN.E, ACROBRYA or CORMOGEN^E with 



a distinct stem, bearing leaves or branches. 

 Sub-class II. THALLOGEN.E, THALLOPHYTA, or CELLULARES 



having no distinct stem nor leaves, but forming A 



cellular expansion of various kinds which bears the 



organs of reproduction. 



THE GROWTH OF PLANTS. 



In considering the growth of plants, we have to distinguish that growth 



which is mere extension of old material from that which is the result of 



the formation of new substance. We have an illustration of the first case 



in the earliest stages of germination of a seed, or in the sprouting of a 



potato in ;i c liar. Growth may and does take place in such instan 



without any real increase of substance, or any augmented weight save 



what may be derived from water. The plant in this stage lives upon the 



reeou: >red up in its tissues, and will continue to do so till they are 



1 But growth, in the sense of real increase of substance or of 



as'.l wri^ht iiMin the addition of new material, depends upon the 



amount of carbon assimilated, as iv forcible to leaves Growth is also 



t'-d 1'V ition of new material with the old by an actual in- 



ln the number of cells. The.-.- indicate tin- ^-neral natur. 

 : h in the organs the root, the stem and the 1 



