THE CENTRAL AMERICAN SPECIES OF QUERCUS \) 



only minor differences in numbers. The configuration of the veins, 

 i. e., whether or not they branch and obviously anastomose, is rather 

 constant and may be depended upon where it presents a difference. 

 Ordinarily, however, closely related species exhibit similar configura- 

 tion. The prominence of the veins is discussed in a preceding para- 

 graph in connection with the leaf surfaces, but there may be added to 

 this the condition in which the veins are scarcely discernible and not 

 very markedly raised on either surface. This occurs usually in 

 rather thick leaves but certainly not in all thick leaves. 



Petioles. — Except for such characteristics as pubescence (which 

 ordinarily simulates that of the midribs or the twigs or both), a 

 pruinose covering, and a winged condition (the blade apparently 

 minutely decurrent on the petiole), scarcely any characters are to be 

 found in the petioles other than length and thickness. Pubescence 

 and the winged condition are subject to the same criticisms as leaf 

 pubescence and shape, but they occasionally prove of value. Petiole 

 length is usually no more dependable a character than leaf shape, but 

 here, too, a great discrepancy is usually significant and especially so 

 if it is constant and correlated with other differences. 



Catkins. — The staminate catkins of Quercus offer few if any 

 characters for use in separating species or groups of species. The 

 length and closeness or laxness of floral arrangement vary too much 

 with degree of maturity to be of much use, although in a general way 

 these characters show some individuality in certain groups. Similarly, 

 the pubescence of the rachis and perianth and the exsertion of the 

 stamens are in part a function of age and only slightly diagnostic of a 

 few isolated entities. 



The pistillate catkins are of use principally in judging whether or 

 not the fruition is biennial. Catkins on twigs of the season lend 

 weight to the evidence of acorns on twigs of the preceding year in 

 deciding that the fruition is biennial. Because the length of peduncle 

 and arrangement of flowers is often the same in the catkin stage as in 

 fruit, these are not of much diagnostic value unless fruiting specimens 

 are lacking. 



Flowers. — Trelease credits the subgenus Erythrobalanus with 

 glabrous anthers and mucronate or apiculate connectives as opposed 

 to the often puberulent and notched or obtuse anthers of Lepido- 

 balanus. However, he states that several series in Erythrobalanus 

 have quite obtuse anthers, and puberulent anthers have been observed 

 as well in that subgenus. The characters are mentioned in the species 

 descriptions merely as a means of recording them in the hope that 

 future collections may yield sufficient authentic flowering material to 

 allow a complete analysis of the floral characters of the genus. 



The pistillate flowers consist of a pistil seated in an involucre and 

 bearing a united perianth of six lobes. The perianth adheres to the 

 pistil up to the point of division of the styles. The lobing does not 

 extend below this point. The subgenus Lepidobalanus is char- 

 acterized by simple erect perianth lobes, but those of Erythrobalanus, 

 although equally erect, are also furnished with a groove beneath the 

 point of insertion. This appears as though each perianth lobe were 

 basally appendaged or spurred and as though the spurs were then 

 fused to form a ring. This then interlocks with the cup scales. 

 Beneath the perianth, the three fused styles and the decurrent 



