viii Iniroduction 



flower type and fixing it in the mind is by means of a formula. For example, the formula 

 for the mustard family is Ca 4 Co 4 S 4 " 2 P( 2 ). For the pea family, it is Ca5 Co 22 -i S 91 P 1 : 

 that is, the calyx has 5 sepals, the corolla 5 petals, wings, keel and standard; there are 10 

 stamens in 2 groups and a 1-ceHed pistil. The parenthesis indicates union of the parts con- 

 cerned, while reversed numbers are used to denote irregularity in shape or arrangement, e. g.. 

 2-2-1 for the irregular corolla of the pea. Differences in level are shown as in the following 



Co 1 

 formula for the evening primrose family : Ca 4 



P( 4 ) 



PRONUNCIATION 



The names of plants, families, etc., are pronounced as in Latin, except that the con- 

 sonants C, g, j and v are pronounced as in English. The sound of the vowels may be indicated 

 as follows : a as ah ; e as ay ; i as ee ; o as oh ; u as oo ; Greek y muth like the German it. 

 The diphthongs are as follows: ae as aye; au as ow in how; oe as oy; ei as ay; eu as eoo; 

 ui as ooee. The accent has been indicated for each name. Quantity has not been indicated, 

 since for the beginner all vowels may well be regarded as long. 



VERIFICATION AND DETERMINATION OF SPECIMENS 



The beginner will necessarily find occasional plants which he is unable to name. Even 

 the student of more experience will now and then find very puzzling forms. In such cases, 

 it is necessary to refer the question to a good herbarium if one is accessible, or to the bot- 

 anist. The department of botany will be glad to have fresh or dried plants sent to it for 

 verification or determination at any time. This applies to mushrooms and other lower 

 forms as well as to flowering plants. Fresh specimens can be sent readily through the 

 mails by wrapping them in moist paper and placing them in a pasteboard box. The depart- 

 ment will also be glad to verify the dried specimens in the herbaria of high schools or of 

 individual students. 



EXPLANATION OF THE CHART 



The chart on page x is designed to show the general lines of descent of flowering plants 

 from the ancestral ferns, and to indicate the relationships of the various orders. It is based 

 primarily upon the development of the flower as a special organ for pollination and seed- 

 production. Families with the simplest flowers, that is, those with the flowers least changed 

 from the fruiting organs of the ferns, are placed at the bottom of the chart. Such families 

 are found in the gymnosperms and in the buttercup order. The flowers of the former are 

 wind-pollinated, and lack both calyx and corolla. The flowers of most buttercups, on the 

 other hand, are pollinated by insects, and possess both calyx and corolla, or a showy calyx. 

 These are regarded as the primitive or earliest type of flower of the ar.giosperms. From 

 the specialization of these, in response to insect and wind pollination, have been derived the 

 orders and families of the three lines of evolution shown in the chart. 



In detail, the primitive flower shows a large number of separate stamens and separate 

 pistils, the petals are alike and separate, and there is no union between any of the four parts, 

 sepals, petals, stamens and pistils. In the increasing adaptation of a flower to its work of 

 pollination and seed-production, this primitive form has given rise to the higher or more 

 specialized forms characteristic of the various orders of the chart. The chief steps by which 

 this has been brought about are four, namely, reduction in number of parts, union, change 

 in shape, change in position of the corolla, or elevation, but these changes have not appeared 

 in the same sequence in all three lines. Reduction in number to a flower plan of 3, 4 or 5 has 

 been almost universal in the groups just above the buttercups, though flowers occasionally 

 occur with number plans of 6. 7, 8 and even 9. In flower structure, the arrowheads are 

 essentially buttercups with parts in threes, while the lilies are arrowheads with the stamens 

 and pistils reduced in number, and the latter united to form a compound pistil. In the irises, 

 tlie colored perianth of sepals and petals is upon or above the ovary, and in the orchids, the 

 corolla is strikingly irregular, one petal usually taking the form of a lip or sack. 



In the roses, the buttercup type is modified by the gradual growing together of the calyx 

 and receptacle, and finally of the ovary also, with the result that the corolla and stamens 



