and Laboratory Methods. 2627 



of free, naked cells. It passes the winter in this condition, and by the following 

 June the archegonia with eggs are ready for fertilization and the pollen tubes 

 have grown down through the nucellus. About the last week in June or the 

 first in July fertilization occurs, and the embryo is matured and in the resting 

 condition in the following autumn. The seed is usually shed late in the winter 

 or in the early spring of the following year. The whole history thus covers 

 nearly three full years. 



LXXIV. Taxus canadensis Marsh. American Yew. 



Class, Coniferae. Order, Taxales. Family, Taxaceae. 



The yew is a low shrub growing on moist banks and hills, especially in the 

 shade of large conifers. It is common northward. Herbarium and alcoholic 

 material may be used if fresh branches are not available. 



1. Sketch a branch, showing arrangement of leaves. Describe. 



2. Under dissecting microscope draw a staminate cone. How are the 

 stamens arranged ? 



3. Draw a single stamen under low power and note the peltate form. How 

 many microsporangia ? Compare the shape of this stamen with the sporophyll 

 of Equisetum. 



4. Under dissecting microscope draw a small fertile branch with a young 

 ovule at the tip. 



5. Cut longitudinal sections of the branch with ovule, mount, and draw 

 under low power, showing the megasporangium in the center surrounded by the 

 long inner integument and a short outer undeveloped aril, with scale-leaves on 

 the stem below. 



6. Draw a ripe seed with the thick, fleshy, red aril. 



LXXV. Higher Gymnosperms. 

 Class and order, Gnetales. 



Study herbarium specimens. 



1. Make a sketch of a small plant of Ephedra ncvadensis Wats. (Family, 

 Ephedraceae.) Note the slender green stems and the dry scale-leaves. In what 

 ways is this plant adapted to a xerophytic' environment ? 



2. Make a sketch of a branch of Gnetuni gnemon L. (Family, Gnetacea^.) 

 Note the large, brood leaves. This is a tropical tree cultivated in India and 

 surrounding regions. John H. Schaffner. 



Ohio State University. 



