T. Holm — Isopyrum bitematum. 133 



Art. XVIII. — Isopyrum bitematum Torr. et Gr. ; an anatom- 

 ical study ; by Theo. Holm. (With three figures in text, 

 drawn from nature by the author.) 



It would be interesting to know the internal structure of all 

 the species of Isopyrum, since it appears as if the genus is not 

 a very natural one, judging from the external characters. As 

 understood by Maximowicz* and Franchet,f Isopyrum com- 

 prises not only all the perennial species with nectaries in the 

 flower, but also the annual Leptopyrum Rchb., and those with- 

 out nectaries, upon which Rafinesque based his genus Ene- 

 mion •% this same disposition we find in the works of De 

 Candolle, Bentham and Hooker. In the so-called Ieptopyru?n 

 fumarioides (L.) Rchb. the stem-leaves are almost verticillate, 

 the nectaries are provided with a scale, the ovaries number 

 about twenty, and are erect, besides that the plant is an annual ; 

 for this reason Prantl§ has kept leptopyrum as a genus sepa- 

 rate from Isopyrum. In the so-called Knemion there is one 

 species, Gray's Isopyrum stip>itatum, in which the ovaries are 

 very distinctly stipitate as in Ooptis, thus differing from all the 

 other members of the genus. However the foliage and the 

 habitus in general of I. stipitatum agrees better with Isopy- 

 rum than with the evergreen Ooptis. In regard to the carpels 

 we find only two and horizontally spreading in I. nipjponioum 

 Franch., or divaricate in I. dicarpon Miq., I. stolon iferum 

 Maxim., I. tracliyspermum Maxim., and I. lauriei Franch. ; 

 in the other species the carpels are mostly erect or very slightly 

 spreading, and never stipitate to such an extent as in I. stipi- 

 tatum. Several, and by no means unimportant, distinctions 

 are furthermore to be observed in the structure of the nec- 

 taries, as described by Maximowicz, for instance in I. ccespi- 

 tosum Boiss. et Hoh., I. dicarpon Miq., and 7. fumarioides 

 L., as mentioned above. In connection with these characters 

 may be pointed out the very peculiar rhizomes possessed by 

 some of these species. Only one annual species is known ; 

 all the others are perennial and herbaceous. In I bitematum 

 Torr. et Gr. the rhizome is very slender and stoloniferous ; the 

 roots are of two kinds, slender in their entire length or monili- 

 form ; in I. occidentale Hook, et Arn. the roots are very num- 

 erous and fascicled, more or less tuberous, but not moniliform ; 



* Diagnoses plantarani novaram asiaticarum, V. (Melanges biol., vol. xi. 

 St. Petersbourg, 1883, p. 623). 



f Isopyrum et Coptis ; leur distribution geographique (Journ. de Botanique, 

 vol. xi. Paris, 1897, p. 154). 



\ Description d'un nouveau genre de plantes, Enemion, et remarques 

 botaniques (Jom-n. dephys., de chim, vol. xci. Paris, 1820, p. 70). 



§Die naturlichen Pflanzenfamilien. Leipzig, 1888, p. 57. 



