16 VERONICA. [CLASS n. OKDEH i. 



length of the calyx. Capsule inversely heart-shaped, compressed, and 

 ciliated. Seed numerous, oval, with a dark sunk spot on one side, 

 convex on the other. 



Habitat. In cultivated ground, banks, xvalls, &c. common. 

 Annual ; flowering May to July. 



This is one of our most variable plants, especially in size : if grown 

 in cultivated ground favourable to its growth, it is frequently found 

 more than a foot in length, much branched at the base, and spreading 

 its branches around it; the leaves of such plants are generally more 

 deeply serrated, and on longer footstalks, with the veins spread out into 

 the leaf from its base. But if grown upon walls, or in situations where 

 thesupplyofnourishmentisscanty,theplantis frequently very small, not 

 exceeding an inch or an inch-and-half in length, erect, without branches, 

 and the whole leaves sessile, oval, (as seen in Fig. 25.) strongly veined, 

 and thickly clothed with pubescence. Although varying so greatly in 

 si/e, its specific characters are constant; and the student will find but 

 little difficulty in correctly referring any of its varieties to its proper 

 station. 



The hairiness of plants we have several times mentioned as being- 

 greater or less according to the situation and soil in which they have 

 grown, a circumstance beautifully illustrative of the means which 

 Nature adopts for the preservation and support of vegetables under the 

 various circumstances in which they are placed. Hairs are composed 

 of transparent cellular tissue, and formed either of a single elongated 

 cell, or of several arranged in a row ; they are either pointed, or divided 

 at the extremity into branches in an elegant stellated manner ; or they 

 are branched along their whole length, presenting a toothed or plu- 

 mose appearance. There are many other modifications of hairs, vary- 

 ing extremely in length, rigidity, &c. They are distinguished by 

 appropriate names, and arranged under two principal divisions, viz. 

 Lymphatic and Secreting : the -former appear to be for the purpose of 

 protecting the younger parts of the plant from cold, and for regulating 

 the process of evaporation from the surface on which they are placed, 

 and where they become points for the attraction of moisture from the 

 surrounding medium. We have already mentioned several instances 

 illustrative of this part of their economy ; it may be added, that plants 

 growing in a situation where a plentiful supply of moisture is afforded, 

 are generally found thinly scattered with, or without hairs ; while 

 other plants of the same species, grown in a hot, exposed situation, 

 with a scanty supply of moisture, and where it is necessary they should 

 be furnished with every means of compensating the disadvantage, are 

 dothed with a greater or less abundance of hairs. On the approach of 

 evening, when the atmosphere deposits its dews, the capillary organs 

 stand erect, and spread themselves out for the purpose of attracting the 

 moisture which they, or the stomata (mouth, or opening in the leaf) } 

 absorb and carry into the system of the plant ; but \\hcn the heat of 



