ILLINOIS NATURAL HISTORY SURVEY MANUAL 1 



naked stem, bearing several pretty violet flowers. We examine 

 the flowers and find 5 green sepals, 5 violet petals, 10 stamens, 

 an unlobed ovary and 5 styles. We will not pick any of the 

 flowers but will sit down among them with our book and turn 

 to the Key to Families, page 30. 



TRACING THROUGH KEY TO FAMILIES 



Starting with number i in the key, we have a choice of three 

 groups of characteristics: "Trees or shrubs, erect," "Shrubs 

 (vines) that climb," and "Herbs." W^e choose "Herbs" and go 

 to the number given, which is 19. At 19 we find a choice of four 

 alternatives, and since the leaves of the plant we have are not 

 abnormal in that they are not curiously shaped and are not 

 scales or spines, we go on as indicated to the number 20. Our 

 plant does not have milky sap, and so we proceed to 22; from 

 there, since its leaves are netted veined, we go to 23. As there is a 

 corolla we go to 24, furthermore the petals are separate, and 

 so we go to 32. At 32 we have "Corolla borne on the receptacle" 

 and "Corolla borne on the calyx." Choosing the first, we move on 

 to 23i and from there, since the leaves are not fleshy, we go to 

 2S- Our plant is growing on land, so that we go on to the next 

 choice at 2^, from which we jump to 41, since the flower has, 

 as we have said, 10 stamens. Here the fact that the flower is 

 perfect sends us to 42, and thence, since the corolla is regular, 

 to 43. Here the 5 violet petals of our flower make us choose 

 "Petals 5" and we go as directed to 45. Here we examine the 

 ovary again, find it not 5-lobed, and go on to 46. Now we must 

 be careful in picking out the line which really describes the 

 leaves of our plant — are they opposite, alternate or basal? The 

 key makes it as easy as possible here, limiting the choice to 

 two, and since we saw in the beginning that our plant had basal 

 leaves, we conclude that we have found some member ot the 

 Wood Sorrel family. Turning to page 175 we find this family 

 begun with a description of the violet wood sorrel, which, as we 

 read, proves to be the plant we have been tracing. 



USE OF KEY TO GENERA 



On some occasions we may have quite a few descriptions 

 within the family to run through before we can be sure ot our 

 plant, and a little more help would be welcome. Let us take 

 such an example, leading through a new set ot signposts in the 

 key. Suppose that on a little later trip, just outside the woods 



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