786 



C. SKOTTSBERG 



representatives of two, Rea and PJioenicoseris. He found the pollen structure so 

 different that he wrote: "These differences are such as to suggest that the two 

 plants may be genetically unrelated ". The investigation was continued and ex- 

 tended by G. Erdtmax who had a much larger material at his disposal, includ- 

 ing all four species of Eudcndroseris, Phoejticoseris phmata, and three species 

 of Rea representing its two sections. Eiidendroseris showed, as could be ex- 

 pected, its own pollen type, different from the kinds described by WODEHOUSE. 

 To my surprise the pollen in D. gigantea, of the monotypical sect. ScJiizoglos- 

 suui, not only differs from that of Enrca, but is very like the pollen o{ Phoeni- 

 coseris, from which, in all other respects, D. gigantea is far removed. I think 

 that Erdtman's statement shows that the three subgenera are connected; it goes 

 without saying that, contrary to Wodehouse's suggestion, they are genetically 

 related. With a narrow genus concept it is easy to break up Dendroseris even 

 without palynological assistance, and in spite of palynological evidence, D. gigan- 

 tea must form its own genus. Dr. Erdtman has been kind enough to supply 

 the following palynological description and key to Dendroseris s. lat. 



Pollen grains slightly flattened diameter including spines 3c — 55 |ji , with 3 equatorial aper- 

 tures situated in small areas apertural lacunae) sligthly depressed under the general surface. 

 These lacunae communicate with 6 ab-apertural lacunae (ab-poral, Wodehouse), 3 in each 

 hemisphere. Non-lacunar parts of surface covered with a more or less undulating spiniferous 

 layer ("sculptine" ; in certain species provided with 6 distinct para-apertural depressions without 

 or with a few spines'. 



I. Longest axis (spines included) 47 — 55]-i. Ab-apertural lacunae usually smaller than apertural. 

 Thin rods connect the spiniferous layer with the inner part of the exine . . Eudenih-oseris 



A. Longest axis 56— 55 |ji. Spines (or, as in the following, the solid apices of more or less 

 spinoid excrescences) about 4 |i. 



1. Sculptine surface only slightly undulating (spines less numerous than in 2) 



))iarginata 



2. Sculptine surface distinctly undulating (spines more numerous than in i) 



))iacraniha, niao-opJiylla 



B. Longest axis about 47 [i. Spines 3 — 4 p.. Ab-apertural lacunae distinctly smaller than 

 in .A /ilora/is 



IL Longest axis 31 — 2)7 V- Ab-apertural lacunae usually not smaller than apertural. No rods 

 like those mentioned under I. 



A. Spines less than 1.5 p.. No distinct apertural depressions. Longest axis 31- — -32 [i 



Rea sect. Eiiren (viicraiitha, pruinataj 



B. Spines 2—4 p. 6 distinct para-apertural depressions. Longest axis 34 — 37 |i. 



1. Spines about 2 jjl, situated on top of distinct rounded protuberances 



Rea sect. Schizoglossiiiit (gigantea) 



2. Spines about 3 — 4 p, situated on top of feeble protuberances 



Pliocuicoseris (phmataj 



Dendroseris D. Don. 1). subgen. Eudendroscris Skottsb. 3.200. 

 Capitula majuscula usque 5 cm lata flosculis aurantiacis. Receptaculum nudum 

 foveolatum foveolis autem fibrilloso-marginatis. Achaenia suberosa, alata, valde 

 dimorpha, marginalibus trigono-alatis a dorso, ceteris a lateribus complanatis. 

 Pappus brevissimus caducissimus. Arbusculae trunco cavo ramoso, foliis rosu- 

 latis simplicibus moUiter coriaceis. Typus: D. macrpphylla D. Don. 



