ROSACEAE, : SILVA OF NORTH AMERICA. 31 
CRAT AGUS. 
In the fourth volume of this work, published in 1892, fourteen species with four varieties of 
Crataegus were described. During the ten years which have passed since that volume appeared, the 
genus has received much attention from the students of trees in the United States, and a large number 
of forms previously unknown have been characterized. A number of these are now described and 
figured in this volume. In addition to these are now known several shrubby species which do not 
necessarily find a place in a work devoted to trees, and a number of trees which are imperfectly known. 
To study these sufficiently to bring them into this Silva would require several years of additional field 
work, and an attempt to include them all would delay perhaps indefinitely the appearance of these 
supplementary volumes. The fact, therefore, must be recognized that this Silva does not include all 
the arborescent forms of Cratzegus which are now known to exist in North America. These must find 
their places in some later work of North American dendrology. 
In this study of the genus particular attention is paid to the number of stamens and the color 
of the anthers as important characters for distinguishing species. The simplest arrangement of stamens 
in the flowers of Crategus is in one series of five stamens which are opposite the sepals and alternate 
with the petals. In certain species these five stamens split, and there are then ten stamens in five pairs 
opposite the sepals, but in some individuals this division is only partial, and flowers of species which 
normally have ten stamens are occasionally found with from seven to nine stamens. In some species 
the one row of five pairs of stamens is supplemented by a second and inner row of five stamens which 
are rather shorter than the stamens of the outer row and are opposite the petals. Some of the stamens 
of this second row may not develop, and the whole number may vary from eleven to fifteen. In 
some species there is a third row of five stamens which are shorter than those of the second row and 
alternate with them. Species with the three rows of stamens have therefore normally twenty stamens, 
but one or more of the inner row may not develop, and species with normally twenty stamens have 
sometimes a number which may vary from sixteen to twenty. In a small group of shrubby southern 
species there is sometimes a fourth row and twenty-five stamens. The flowers of Crategus then 
have normally five stamens in one row, ten stamens in one row of five pairs, fifteen stamens in two 
rows, twenty stamens in three rows, and rarely twenty-five stamens in four rows, the number in each 
group varying by the suppression of one or more of the stamens. 
The color of the anthers, which are either pale yellow or various shades of rose color or purple, 
generally affords a constant specific character. In Crategus punctata, however, the anthers are rose 
color on some trees and yellow on others, trees with yellow anthers usually producing yellow fruit and 
those with red anthers red fruit. In some parts of New England there is a Thorn which is still very 
imperfectly known, and which apparently differs from Crategus prwinosa with its rose-colored anthers 
only in its pale yellow anthers, and there are indications that Crategus Crus-galli in the middle states 
and in Missouri sometimes at least has flowers with yellow anthers. But these variations, except in the 
case of Crategus punctata, must not be considered conclusive, for it is not improbable that besides the 
color of the anthers there may be other characters which will make it possible to distinguish these plants 
specifically. Flowers with from five to ten stamens usually have two or three styles and nutlets, while 
the species with fifteen stamens or more have generally five but often four styles and nutlets. There are, 
