10 MISC. PUBLICATION 4 7 7, U. S. DEPT. OF AGRICULTURE 



perianth bases form a stylopodium which persists as a knob on the 

 apex of the mature fruit. This stylopodium is subtended basally 

 by a three-carpellate ovary and apically by the three free styles and 

 stigmas. 



Besides the basally grooved perianth of Erythrobalanus the only 

 character of the pistillate flower that is of value taxonomically is the 

 nature of the stigmas. In Lepidobalanus the stigmas are broad, 

 abruptly dilated, and reflexed or abruptly spreading; in Erythro- 

 balanus they are more narrow, gradually dilated, and more gradually 

 spreading. 



It is clearly evident from the foregoing remarks that almost the 

 only characters of taxonomic value to be found in the flowers are 

 those that distinguish the two subgenera. An exception to this may 

 be seen in the anthers, which are puberulent or glabrous and apiculate 

 or not, irrespective of subgeneric lines (except that the apiculate 

 anthers are largely confined to Erythrobalanus and the puberulent 

 anthers to Lepidobalanus, there being exceptions in both cases). 



Fruit. — In most cases the distinction between annual-fruited and 

 biennial-fruited species is a good one. All the species of Lepido- 

 balanus are strictly annual-fruited, but in Erythrobalanus certain 

 series are annual, certain biennial, and still others contain both annual- 

 fruited and biennial-fruited species. In a few instances species 

 ordinarily characterized by annual fruition may appear biennial 

 fruited as a result of renewed growth late in the growing season. 

 This circumstance likewise causes an apparent evergreen condition 

 in characteristically deciduous species. Rarely the failure of the 

 terminal bud to resume growth may give a biennial-fruited evergreen 

 species the appearance of annual fruition. 



Although length of peduncles is an unstable character, there is in 

 Lepidobalanus a distinct break between obviously pedunculate species 

 and those with subsessile fruit. In Erythrobalanus such a distinction 

 apparently is impracticable. 



The fruit is composed of a nut seated in an involucre. The nut 

 (acorn) is derived from a three-carpellate ovary each carpel of which 

 contains two or rarely three ovules. A single ovule develops, and 

 the remainder abort and remain attached to the integument of the 

 one functional ovule. The position of the aborted ovules, i. e., 

 whether they adhere to the apex or the base of the functional ovule 

 or in a lateral position, would probably be a character of considerable 

 value, if its distribution in the genus were thoroughly known. In 

 general, the abortive ovules of Lepidobalanus are strictly basal or 

 somewhat lateral, whereas those of Erythrobalanus are apical in most 

 species. A few groups of species in Erythrobalanus characteristically 

 have basal or lateral ovules. However, in Q. acatenangensis , a species 

 with ordinarily strictly apical abortive ovules, individuals have been 

 observed with clearly basal ones. Also in Q. boqueronae, a species of 

 Lepidobalanus, the aborted ovules are very deeply lateral or basal, the 

 several sets of ovules being scattered along half the length of the 

 functional ovule. It is clear, then, that the position of abortive 

 ovules can scarcely be relied upon as a distinction between the sub- 

 genera, although it holds true in a high percentage of cases. 



Much more trustworthy is the condition of pubescence of the inner 

 surface of the acorn shell. In Lepidobalanus the shell is completely 



