112 ROBERT TRACY JACKSON OX 



Oak (Fig. 62). The cotyledons remain in the acorn beneath the surface as in the White 

 Oak and some other, perhaps all, species of the genus. The petioles of the cotyledons 

 extend beyond the acorn, embracing the stem, as shown in the seedlings figured. In 

 Fig. 67 the thick, rounded cotyledons are shown with the acorn husk removed. The 

 first few leaves are reduced to scales, axillary buds being the most prominent feature. 

 The first leaves developed (PL 20, figs. 67, 68) vary in size, are ovally rounded, and bear 

 a minute tooth at the end of the median rib, but are otherwise entire. While the speci- 

 mens figured represent typical individuals, sometimes the first leaves have minute teeth at 

 the end of a few lateral veins as well as the median vein ; in such specimens the leaf may 

 or may not have a slightly flexuous margin. In Fig. 67, the first three leaves have only 

 a slight tooth at the distal end, the fourth leaf has a slightly sinuous mai'gin, and minute 

 teeth at the tips of principal veins. In Fig. 68, the first two leaves are entire and smaller 

 than the average. The next two leaves have sinuous margins and teeth at the ends of 

 principal veins. In later growth the leaves become more deeply lobed with pronounced 

 bristles. The leaves of these young oaks are rather bright green, lusterless, covered with 

 fine hairs arranged in a stellate manner. If the growth of the first year dies, a new 

 growth springs up from the base, which is indistinguishable from an actual seedling, and 

 this may happen several times. I have frequently dug up such relatively old plants for 

 seedlings and not found the mistake until tlie scars of previous growths were seen. That 

 is, at this localized area nepionic leaves are pi'oduced continually, as in many other 

 plants, although the plant may actually be several years old. 



Suckers from the base of an adult Black Oak usually have leaves near the base of the 

 sucker which are simple in outline (PL 20, fig. 69), or .slightly lobed and with small 

 teeth (PL 20, fig. 70). Succeeding leaves become rapidly more lobate and bristly (Fig. 

 69), but do not acquire the full character leaves of the species (PL 20, fig. 71) for a con- 

 siderable distance from the base. As Emerson ('46) says of the form of the leaves in 

 this species, " * * * on young and vigorous shoots, particularly on spi-outs from a stump, 

 more nearly entire." Suckers from the base of the Scarlet Oak have leaves of the same 

 form as in the Black Oak. 



In the above oaks, then, in suclcers and in vigorous growths from the stump, the 

 leaves are more entire or simple than the typical leaves of the several species, thus mak- 

 ing an approach to the simplicity of the seedhng in a greater or less degree. The fossil 

 oaks of the Cretaceous (Lesquereux, '91), and Tertiary are simple in outline or slightly 

 toothed. The seedUngs, suckers, etc., of the species discussed are therefore in their sim- 

 pUcity comparable to ancient fossil allies. As the Swamp White Oak and Chestnut Oak 

 are simpler in outline than the Black and Red Oak ty])es, they make a nearer approach 

 to the characters of seedlings, suckers, and earl}^ fossil oaks, and may, therefore, be con- 



