146 Observations on the Genus Spathium. [No. 122. 



of germination, and its solid cotyledon — while there are the minor 

 differences of the relvaceous foliage and caducous bracts of the for- 

 mer, as contrasted with the herbaceous foliage and persistent bracts of 

 the latter. There is, moreover, a slight difference in the pollen of 

 the two plants, that of the former being exactly and acutely elliptic, 

 and assuming a globular form under the influence of acid or iodine ; that 

 of the latter gibbously ovoid, and not influenced in the same manner by 

 the iodine solution or acid. 



From the description of Aponogeton pusillum in Roxburgh's F. I. 

 and the section of the fruit of A. echinetum, in his Cor. Plants, t. 81, 

 I should judge that they would have the same characteristics as the A. 

 undulatum. They may perhaps be found to be intermediate, in which 

 case the two species I have examined may be fairly considered as the 

 extremes of a single genus. From the general habit, and the position of 

 the bracts of Endlicher resembling that of half a floral envelope, for 

 which reason I term them sepals in the description, the place of this 

 genus would appear to be next to Potamogeton among the Naides. 



I have subjoined an amended generic character, and fuller descrip- 

 tions of the two species I have examined. 



Spathium Loureiro. Endlich. Gen. 1826, p. 267. 



Floris hermaphroditi, in spadice cylindraceo pedunculato spatha mo- 

 nophylla caduca cincto spiraliter dispositi sessiles. Sepala duo peta- 

 loidea sub-opposita. Stamina sex, hypogynse ; filamenta libera subulata 

 patentia persistentia, antherse bilocularis lateraliter dehiscentes. 



Ovaria tria (vel. 4 ?) rostris erectis, stigmate apicale, minutum ob- 

 liquum ; ovula basi afhxa 2-6, ascendentiee. Folliculse 3 (4 ?) intror- 

 sum dehiscentes, 1-3 spermse, semina erecta ovata; testa duplici, ex- 

 teriore herbacea, interiore membrancea, vel evanida. Embryo exalbu- 

 minosus macropodus, erectus, ascendens, anatropus cotyledine magno, 

 vario, plumula varia. 



Sp. monostachys. Foliis petiolatis lineari, oblongis basi subcordatis 

 emersis herbaceis. Floribus in spadice dense confertis sepalis persis- 

 tentibus. 



Rhizoma tuberosum radicibus crassis filamentosis ad apium rhizo- 

 matis. Folia petiolata, petiolis subtrigonis basi membranaceis interioria 

 amplectentibus, folia lineari, obliquus obtrusis, basi subcordatis, vel junio- 

 ribus cuneatis, 5 nerviis, venis transversalibus^ 



