NOTES ON NORTH AMERICAN SPHAGNUM. IV 



A. LeRoy Andrews 



The Section Malacosphagnum Carl Muller 



The plants of this small section present, when once known, a fairly distinct 

 aspect in the field, due in part to a compact manner of growth with branches 

 more or less erect, and more especially to the large size and relative thickness of 

 the leaves together with their washed-out whitish to glaucous green color effect, 

 features which altogether give to plants of this section more the appearance of 

 tufts of Leucohryum than is the case with any other species of Sphagnum. The 

 plants may, however, even show something of a brownish pigmentation. The 

 essential characters of this section have been indicated in a previous note; with 

 reference to the leaves it may be said that the branch leaves show the border in 

 process of differentiation rather than as an accomplished fact, in that the outer 

 chlorophyll cells form a fairly straight line and that the hyaline cells next within 

 may be extremely narrowed to the point of losing their fibrils or may even be sup- 

 pressed altogether, so that in places two chlorophyll cells joined form a border much 

 as in Acisphagnum. The outer chlorophyll cells show the resorption-furrow as in 

 Inophloea. The stem leaves possess the border of several rows of narrow cells 

 with pitted walls characterizing Acisphagnum. The perichaetial leaves are par- 

 ticularly irregular, in that they resemble branch leaves more than is usually the 

 case. They are, it is true, larger than normal branch leaves, but they are closely 

 disposed at the base of the weak and short pseudopodium, somewhat spreading 

 rather than closely clasping, generally more or less falcate-subsecund and have a 

 form and areolation but slightly differing from that of the branch leaves. They 

 have, however, a clearly differentiated border of narrow cells with pitted walls 

 and lack the resorption-furrow. The hyaline cells next within this border are 

 narrower, lack fibrils and commonly show a membrane gap in about the center 

 of the inner surface. The stem leaves show in the same way resorption of mem- 

 brane on the inner surface of hyaline cells, in case these are non-fibrillose, in- 

 stead of on the outer surface as in Inophloea. Antheridia have mostly been 

 noted only on the weaker pendent branches, though Warnstorf now ascribes 

 them to the spreading branches as well, but as the antheridial leaves are in no 

 way differentiated they are extremely hard to find. This section is also distri- 

 buted widely over the earth. 



8. Sphagnum compactum De Candolle, 1805. This old name of the species 

 was again saved by Lindbergh as against 5. rigidum Schimper, 1857, the identity 

 being satisfactorily established by the figure of Schwaegrichen^ drawn from a 

 specimen sent to Hedwig by De Candolle. Apart from the general characters of 

 the section Malacosphagnum already noted, the species is distinguished by the 

 nearly central and nicely included chlorophyll cells of its branch leaves, which 



1 Europas och Nord-Amerikas Hvitmossor 41. 1882. 



2 Supplement I, /// (part). 1811. 



