KUNGL. SV. VET. AKADBMIENS HANDLINGAK. BAND 55. N:0 5. 



69 





'S5.^'B?Sq^M8M' 



, a 



of the pistils is met with though not so regularly. Finally the fuUgrown 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 shown by the fig. 26, A. The epidermis-cells of P. zosteri- 

 folius are constantly short, 1,5 — 3 

 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 lacuna3 



arp mnrp cjnnarp anc\ Invv in thi'? ^'6- 26. J-, B, C. P. acutifoUm Link. D, E, P. zosterifolius Schum. 



are more square ana lOW, m rniS _ ^^ i-i-ansverae section of the stem, y^; the dotted line indicates the 



of a more rectano'Ular crosscut occisionally occurring depression by which the stem becomes narrowly 



*-' double furrowed. B, Transverse sect, of the rhizome, ^/. Obs! the terete 



form and the lacunar part thus form! C, Longitudinal section of the stem-epidermis, ''f. — D, Longitu- 



, . ■. J 1 1 dinal sect, of the epidermis of the stem, 'V°- ^< Transverse sect, of the 



more elevated over the lower sur- stem, V; the dotted iinos, see a! 

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



In anatomical respect the leaves are essential^ of the same structure except that 

 P. zosterifolius always has two lateral vascular bundles, whereas P. acutifoliiis 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 over the sheaths. In the other species, again, the buds are 



