344 



PART IV. VEGETABLE TAXONOMY. 



B 



Fig. 553. — Andrsea. A, fruiting 

 plant: B, capsule, magnified; C, 



(B) The Andraeacese. This is a small order of dark 

 colored, branching mosses, of rather diminutive size, mostly 

 growing on damp rocks in mountainous regions. They produce 

 capsules which have a closely adherent, thin calyptra, and a 

 central columella, which is free at the apex ; they dehisce longi- 

 tudinally into four or rarely six valves. These separate in the 

 middle to shed their spores, but remain united both at the base 

 and apex. See Fig. 553. The capsules 

 are stalked, but the stalks are formed 

 as in the Sphagnums. 



(C) The Bryaceae constitute by 

 far the largest as well as the best devel- 

 oped order of Mosses. It is one of this 

 order that is illustrated in Figs. 541 to 

 545, inclusive. They are usually low, 

 tufted plants, with generally cylindrical 

 or rarely slightly compressed or some- 

 what angular, leafy stems. The leaves 



are simple, and, in some species, com- dehiscent capsule and calyptra 

 posed of but one stratum of cells ; in others, of more than one ; 



in some, the leaves are nerveless, in others 

 there is a single median nerve, and in still 

 others two small nerves at the base. 



The reproductive organs are, in most 

 cases, enclosed in a perichaetium or peri- 

 gonium ; the capsule is traversed perpen- 

 dicularly by a columella which is attached 

 both above and below ; in a very few species 

 the capsule either does not open at all or 

 breaks irregularly ; in the great majority it 

 dehisces by means of an operculum. The 

 orifice thus exposed is sometimes naked, but 

 in most cases has a peristome. The latter 

 may either be single or double, having one 

 The outer peristome 

 consists of a row or circle of teeth which, in 

 different species, vary in number from four to thirty-two or 

 more. The inner peristome, if present, consists of a yellowish 

 pellucid membrane, which is often latticed, and attached to the 



Fig. 554. — Capsule of 

 Fontinalis, one of the Bry- 

 acea:, with calyptra and 

 operculum removed.show- 



T£:J:t 1 ^^ p art within the other 



tome. Magnified. 



