Chapter XXI. 



Ground-hemlocks and various Pines, 

 if 



Of lower seed-plants there are five living and at least two 

 extinct families. In Minnesota but two of the five living fam- 

 ilies are represented. These are the yews and the pines. 



Ground-hemlocks. The yews are represented by a single 

 species, the ground-hemlock, a well-known plant of wooded 

 banks and forests throughout most of the state. In England 

 a species of yew exists which becomes a large tree, but of the 

 four species in America none reaches any very great size, and 

 the ground-hemlock is the smallest of the group. It is an ever- 

 green shrub with leaves much like those of the balsam, and rec- 

 ognized by its crimson berries the size of small gooseberries. 

 The berry of the yew, however, is not a fruit but a seed, sur- 

 rounded by a red pulp-cup which may be regarded as a basal 

 outgrowth. Of all seed-producing plants in the state the yew 

 gives its seeds the least protection. In pines the seeds are en- 

 closed by the scales of the cone, and in all higher seed-plants the 

 seeds are developed within fruits and are never, from the first, 

 exposed, as in the ground-hemlock. The red pulp which en- 

 circles the yew seed makes it attractive to birds and it is dis- 

 seminated by their agency. Besides the seed-rudiments on 

 the branches, the yew produces little round cones consisting of 

 axes upon which are borne a few shield-shaped leaves. Each 

 of these resembles the spore-producing leaves of the scouring- 

 rush and on the under side of each a circle of pollen-spore-cases 

 are developed. The yew plants, of all Minnesota seed-bearing 

 forms, produce the largest number of pollen-spore-cases on a 

 single stamen. Usually the number is four, often but two, while 

 in the yew the number may be six or even more. The micro- 

 scopic male and female yew plants are short-lived, but the spore- 

 producing plant, beginning as an embryo in the seed, then after 



