WEEDS OF MAINE. 285 



Class V.— PLANTS WITH NO DISTINCTION OF STEM AND 



FOLIAGE— Thallophytes. 



It was not our intention to notice these mostly minute organisms, 

 considering them entitled to an article by themselves. Therefore 

 we will only mention a few of the more important species. 



Order 43. LICHENES — Lichens. No species of this order can 

 be considered as weeds. They grow on the ground, on the bark 

 of trees and on rocks. They draw their nourishment directly from 

 the air. 



Order 44. MUSHROOMS, MOULDS, ETC— Fungi. Plants 

 of this order are parasitic, generally drawing their nourishment 

 from living, though more commonly languishing plants and ani- 

 mals ; but often appropriating the organized matter of dead and 

 decaying animal and vegetable bodies. Puff-balls and mushrooms 

 belong to this family. 



Gooseberry Cluster-Cups {^cidium Grossularice) may be found 

 on the leaves and fruit of the Currant and Gooseberry in June. 



Mildew or Rust {Fuccinea Graminis) is often very injurious to 

 the herbage of corn, grains and grasses, in damp muggy weather. 



Blight, Smut or Brand ( Ustilago segetum, Ditm.) is the cause of 

 much damage to the ears of corn and grain, filling the kernels with 

 a copious black dust. 



Bean Rust (TWc7io6as2S i^a6«?). On beans in August and Sep- 

 tember. 



Potato Mould {Peronospora infestaus). Very common since 

 about the year 1845, on the leaves, stems and tubers of the potato, 

 causing the potato murrian, 



Erysiphe llartii, is the mildew or blight which effects the leaves 

 of peas, imparting to them a chalky appearance. 



SHRUBS. 



In the foregoing pages we have noticed, with one exception, only 

 herbaceous plants, thinking it more eligible to notice the shrubs 

 by themselves. 



1. Foisoif SuyiACBi^Ehus venenata. A shrub or small tree, fre- 

 quent in swamps and low grounds. The trunk is often several 

 inches in diameter. The leaf-stalks are red, bearing seven to thir- 



