108 



MEMOIRS- OF THE NEW YORK BOTANICAL GARDEN 



[vol. 10 



hydroxide, a reagent commonly used in pollen-preparation techniques, partly 

 or wholly dissolves the exine. Except for two specimens (figs. 112, 120) in which 

 XaOH treatment was very gentle and merely revealed some textural differen- 

 tiation in the exine — probably because of preferential solubility of certain 

 parts — this substance proved useless. Even the pollen of fixed material which 

 formed the main basis for this study was, in some cases, altered. Because of 

 this extreme sensitivity to a wide variety of reagents, the simplest methods for 

 preparation of pollen grains for observation appeared to be (1) sectioning and 

 staining of flowers (with their included pollen) according to the techniques 

 described at the beginning of this paper; and (2) transferring fixed anthers 

 through an alcohol series to absolute ethyl alcohol, staining in safranin dissolved 

 in absolute ethyl alcohol, and following this by transferring anthers to xylene 

 and making whole mounts of grains in Canada balsam. l T ndoubtedly both of 

 these techniques resulted in dehydration and perhaps other changes which could 

 alter size and possibly induce artifacts. However, a number of grains in each 

 of the collections studied appeared to be reasonably unaffected, and were con- 

 sidered suitable for study. Note should be made of the fact that the spines (or 

 other excrescences of the exine) that stain bright red are seemingly unchanged 

 by any of the reagents mentioned, and data concerning these are without doubt 

 quite reliable. The exine wall, which stains green with a safranin-fast green 

 combination, is the structure that is sensitive to reagents. 



Because the grains are large, and few in number per anther, because good 

 material (grains from anthers just before or at anthesis) were necessarily 

 limited, and because many grains were collapsed, or degenerate, the number of 

 grains that could provide reliable measurements was extremely small. The data 

 on pollen grain diameter below represent, therefore, averages of measurements 

 of only those grains that the writer judged to be turgid and otherwise unaltered 

 in form. On account of the exceptional susceptibility of pollen grains in this 

 family to various changes, truly exact data can probably be obtained only from 

 fresh material. Such material is virtually impossible to view because of the 

 remote locations in which these species grow. Terminology for pollen morphology 

 used below follows the usage of Erdtman (1952). 



Pollen Grain Size. 



Pollen^grains of Abolboda, Orectanthe, and Achlyphila are sphaeroidal, a 

 fact which may be related to their nonaperturate condition. Because of this 

 shape, only one dimension is necessary. Dimensions do not include the spines 

 or other excrescences. 



Species 



Abolboda acaulis (fig. 106) 



A. acicularis var. acicularis (fig. 107) 



A. bella (fig. 108) 



A. cilmta (fig. 109) 



A. ebracteata (fig. 110) 



A. grandis var. guayanensis (fig. Ill) 



A. linearifolia (fig. 112) 



A. macrostachya var. angustior (fig. 118) 



A. macrostachya var. macrostachya (fig. 119) 



1) ia m eter in microns 



84 

 96 

 110 

 96 

 90 

 150 

 120 

 155 

 105 



