KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. N:0 5- 89 



the fruit smooth, back often without perceptible keel, but sometimes with a keel, 

 now without, now with teeth or bosses. 



The stem-anatomy of the species of this group is rather uniform. A pseudo- 

 hypoderma is rare, subepidermal bast-bundles, on the contrary, are alvvays present. 

 The endodermis of this group, as is the case in the foregoing and following ones, 

 consists of typical O-cells. The bundles of the central cylinder sometimes fuse into 

 a compound bundle (circular diagram), more often they run separately in three groups, 

 the lateral bundles being free from the two median ones and these always as to the 

 xylem-parts fused and consequently with a common xylem-cavity (the oblong diagram). 



I divide the Pusillus-grou^ into two series: Pusilli connati et convoluti, the 

 latter series into two subseries: Acuti and Obtusi according to the leaf-apex being 

 acute or obtuse. 



Series A. Pusilli COnnati: Vaginse stipulares connatse ochreatse, non plicatae. 

 Folia acute ± longe cuspidata vel sensim attenuata ut plurimum ± rigida. 



Of hereto belonging species P. foliosus stånds more apart and separate from 

 all the others by its short peduncle and peculiar crested fruit, the lid of which is 

 sharply keeled. P. li?nosellifolius, which ought to be put here, forms the transition 

 to the Javanici by its more differentiate upper leaves. 



Series B. Pusilli convoluti." Vaginse stipulares fissse convolutae. 



We have a transition-f orm to the Javan. within this series also, viz. P. Preussii. 



Subseries a. Acuti: Folia caulina ± acute ± longe cuspidata vel sensim attenu- 

 ata ± rigida. 



Subseries b. Obtusi: Folia caul. ± obtusa ± läxa, cuspide minore. 



Series A. Pusilli connati Hagstr. 



The rigidity of the leaves is produced by the structure of the nerves which 

 are very prominent in the lower surface, and by the numerous subepidermal bast- 

 bundles in the lacunar system and strong marginal strands. 



P. foliosus Rafinesque. 



Medical Repository, 2d hex. V, 1808, 354. — P. pmiciflorus Pursh, Fl. Americae 

 Septentr. I, 1814, 21. Fig. 1, L, 35. 



The stem is flattened in the relation of 2 — 3:1 with rounded margins, and its 

 anatomic structure is in accord with that of several other Pusilli being characterized 

 by a circular stele-diagram. In the peduncle, on the contrary, the four vascular 

 bundles usually do not spread as in some other species, but continue as a compound 

 bundle with four phloem lots, separated by a mechanic tissue and surrounded by a 

 common sheath or endodermis. In the middle the xylem dissolves into a common 

 channel. Sometimes, however, the fusion of the bundles is not so complete, but 

 nevertheless they run so near to one another that their sheaths fuse into a common 



K. Sv. Vet. Akad. Handl. Band 55. N:o 5. 12 



