Minnesota Plant Life. 137 



Umbrella-liverworts. Related to the cone-headed liverwort 

 is the umbrella-liverwort, growing in localities similar to those 

 favored by the plant just described. The flat stem is a little 

 smaller, usually not of so dark a green, with somewhat crumpled 

 margins and less conspicuous diamond-shaped areas on the sur- 

 face. In this species the special branch which bears the ring of 

 capsular plants has a head shaped somewhat like an umbrella 

 with thick ribs but without a covering. The branch bearing 

 the spermaries is larger with broader top than in the cone- 

 headed liverwort, and after the spermaries have opened to re- 

 lease their sperm cells the general spermary-bearing branch 

 elongates. 



Purple-edged liverworts. In still another liverwort related 

 to the two described, the plant-body is still smaller, averaging 

 about a quarter of an inch in width and an inch or two in length, 

 but distinguished by the same flat prostrate habit of growth, the 

 same notched branch tips and the same little diamond-shaped 

 areas upon the upper surface. This, from the color of the mar- 

 gins of its flat branches, may be called the purple-margined 

 liverwort. Its special erect stems are shorter and more delicate 

 than in the varieties before mentioned. The head which bears 

 the capsular plants is rather flat, of somewhat square outline, 

 and usually supports but four of the spore-producing capsular 

 plants of the life-history. 



Besides these, which are among the commonest forms in the 

 state, there are a few others related to them but less likely to be 

 encountered. 



Cuplets and gemmae of the umbrella-liverwort. The um- 

 brella-liverwort just mentioned is remarkable among species 

 native to Minnesota for its production of curious tiny propaga- 

 tive branches clustered together, a score or more in a group, 

 at the bottoms of little cups from a sixteenth to an eighth of an 

 inch in diameter and borne upon the upper surface of the sex- 

 ual plant-body. These little cups have a bottom composed of 

 a layer of cells some of which bulge out from the general surface 

 and divide into a stalk- and a head-cell. The head-cell then 

 produces a small convex organ shaped somewhat like a pair of 

 watch crystals placed with their concave surfaces together and 

 notched at the sides. Such bodies are called gemmae. They 



