KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55- NIO 5. 



69 



of the pistils is met with though not so regularly. Finally the fullgrown peduncle 

 of typical P. zosterifolius is more elongated, usually 3 — 6 cm (2.5—11), in P. acuti- 

 folius on the other hand always short, usually about 10 mm (5 — 23). In both spe- 

 cies the crosscut form is alike. The median vascular bundles of P. zosterifolius 2—4, 

 those of P. acutifolius always only two. 



The greatest differences are to be found in the stem, the leaves and turios. The 

 crosscut-form of the stem is shownby the fig. 26, A. The epidermis-cells of P. zosteri- 

 folius are constantly short, 1.5—3 



A 





S?SP8<2.L>> 



>'^m&Mmm 



times as long as they are broad, 

 those of P. acutifolius again con- 

 stantly long, 4 — 6 times (or more) 

 longer than broad, fig. 26, C, D. 

 The stem of both species is often 

 faintly bicanaliculate, by which 

 these, like many of the following ~ 

 species, exhibit relationship to P. 

 crispus. As in this species the 

 furrows disappear in the peduncle. 



Proportionally the leaves of 

 P. zosterif. are longer than those 

 of P. acutifolius, the involucral 

 ones of that being 60 — 90 mm, 

 and of this 30 — 60 mm. In P. 

 acutifolius the central lacunar part 

 of the leaves occupies the space 

 between the two lateral nerves in 

 the lower half or third part of the 

 leaf, in P. zostif. only in the mere 

 basal part. In that the lacunae 

 are more square and low, in this 

 of a more rectangular crosscut 

 form and the lacunar part thus 

 more elevated över the lower sur- 

 face of the leaf (fig. 25, A, D). 



In anatomical respect the leaves are essentialty of the same structure except that 

 P. zosterifolius always has two lateral vascular bundles, whereas P. acutifolius has 

 only one bundle on either side, this consequently being »3-nerved» and that »5-nerv- 

 ed>. In both species numerous subepidermal bast bundles are met with, the mar- 

 ginal ones being very strong. As to the leaf-apex these species hardly can be dis- 

 tinguished from each other, though P. acutifolius usually has more elongated cusp 

 and free nerve-tops. 



The turios of P. acutifolius are thinner and their inner leaves not at all, or 

 but little, protruding över the sheaths. In the other species, again, the buds are 



Fig. 26. A, B, C, P. acutifolius Link. D, E, P. zosterifolius Schum. 

 — A, Transverse seetion of the stem, \$; the dotted line indicates the 

 oceasionally occurring depression by which the stem becomes narrowly 

 donble fnrrowed. B, Transverse seet. of the rhizome, 7 T °. Obs! the terete 

 form! C, Longitudinal seetion of the stem-epidermis, "j". — D, Longitn- 

 dinal sect. of the epidermis of the stem, G j. E, Transverse sect. of the 

 stem, Y'l tlie dotted lines, see A! 



