2 KEY AXD FLORA 



the genus lias been reached, presents no difficulty in a little 

 flora like the preseQt one. 



A single example may suffice to illustrate more iu detail 

 the manner of determining species. Suppose the student to 

 have in hand a flowering specimen of lily of the valley. Turn- 

 ing to the key, page 5, it is evident from the statements con- 

 cerning Gymnosperms that the plant does not belong under 

 that head. Under Angiosperms it is clear, from the numerical 

 plan of the flower (in threes) and the parallel-veined leaves, 

 that the plant is a Monocotyledon. Among Monocotyledons 

 • three general groups are designated by as many numbers in 

 parenthesis. The flower in hand belongs under (.3) " Flowers 

 not on a spadix." Under this head the choice is first be- 

 tween (a) "Carpels numerous and separate" and (h) "Carpels 

 united." In the lily of the valley they are united. The next 

 choice is between " * Perianth hypogynous " and " ** Peri- 

 anth not hypogynous.'' This flower is hypogynous. The 

 families with hypogynous perianth are grouped under three 

 divisions (distinguished by f, ft, ttt respectively), and of 

 these the last, with its "Perianth actinomorphic, its divi- 

 sions all alike or nearly so, petal-like," corresponds to the 

 flower under examination and refers the student to "10. Lily 

 Family, page 6." Turning to the key to the genera of the 

 Lily family, page 31, two subfamilies are found. Since the 

 plant is not a climber it belongs to " Subfamily I. Liliacese 

 Proper." 



This subfamily is divided into five groups designated by 

 capital letters. The lily of the valley has an undivided style 

 and springs from a rootstock, therefore it belongs to group B. 

 Beading the descriptions under B, none is found to agree with 

 the plant in hand until the next to the last is reached : " Leaves 

 only 2, directly from the rootstock. Flowers in a raceme, bell- 

 shaped, white, sweet-scented, Convallaria." 



