244 The Ohio Naturalist. [Vol. XI, No. 2, 



The leaf-markings distinguished in the second group, namely, 

 those depending on some structural peculiarty, are perfectly 

 normal and may also be present generally or onh^ on some indi- 

 viduals. The leaves ma}' be covered with minute spots or dots 

 caused by internal glands as in Hypericum maculatum where the 

 dots are often black or dark blue, and as in Boebera papposa 

 where they are oval in shape and of an orange color. In most 

 species the dots or punctations are, however, too small to be seen 

 by the unaided human eye, although conspicuous under a lens. 

 Nelumbo lutea has a peculiar light-colored marking in the center 

 of the large peltate leaf that has some resemblance in outline to 

 certain species of beetles. The marking is purely structural and 

 accidental, yet were green beetles in the habit of freciuenting 

 these leaves it might be cited as a remarkable case of mimicry. 



The most common markings of this general type are those 

 which follow the venation of the leaf -blade, often forming retic- 

 ulations. Examples of species with red A'cins and reticulations 

 are Hieracium venosum, Viola hirsutula, and Rumex obtusifolius. 

 Argemone mexicana is perhaps the most striking example among 

 those with white markings over the veins. The leaves of Mitchella 

 repens show a pale-green narrow stripe over the midrib and 

 Euphorbia nutans has ]3art of the midrib marked by a white 

 streak. The leaves of Peramium pubescens has a beautiful white 

 reticulation over a dark-green background, with occasional white 

 blotches. 



The most interesting examples of leaf workings, however, 

 come in the third group designated above. In the first jjlace, the 

 leaf blade may be some permanent, uniform color other than 

 green. Oxalis rufa is a plant of this character. The color in 

 such cases may have a physiological use in protecting the 

 chlorophyll. 



Numerous leaves have a silvery mottled or blotched appear- 

 ance of more or less definite pattern. Among such are the fol- 

 lowing: Hydrophyllum appendiculatum, H. macrophyllum, H. 

 virginicum, Hepatica hepatica, H. acuta, and Chimaphilamaculata. 

 vSmilax glauca has the same type of markings at least in the young 

 condition. Cucurbita pepo and C. maxima ha\'e ijrominent 

 angular silvery patches, covering the leaf blade, in the angles of 

 the veins. In the Hydrophyllums, the main variegation usually 

 extends on each side of the midrib and occurs in smaller spots 

 beyond, especially at the notches of the serrations. 



Other plants having mottled or blotched leaves are Erythro- 

 nium americanum, E. albidum, Lamium album, L. maculatum, 

 Trillium sessile and T. recurvatum. In Trillium sessile the 

 markings are usually very prominent, while in T. recurvatum they 

 are not always visible. Arisaema triphyllum has beautiful red- 

 dish-bro^\'n and whitish spots on the sheathing bracts, petioles, 

 and ]jeduncles but the leave blades are green. 



