Band 137. Nr. 15. XXXIX. Jahrgang. I. Bd. Nr. 15. 



Botanisches Centralblatt. 



Referierendes Organ 



der 



Association Internationale des Botanistes 

 für das Gesamtgebiet der Botanik. 



Herausgegeben unter der Leitung 

 des Präsidenten: des Vice- Präsidenten: des Secretärs-. 



Dr. D. H. SeoU. Prof. Dr. Wm. Trelease. Dr. J. P. Lotsy. 



und der Redaciions-Commissions- Mitglieder : 



Prof. Dr. Wm. Trelease, Dr. C. Bonaventura, A. D. Cotton, 



Prof. Dr. G. Wehmer und Mag. C. Christensen. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern, 



Dr. J. P. Lotsy, Chefredacteur. 



No. 15. 



Abonnement fOr das halbe Jahr 15 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1918. 



Alle für die Redactiou bestimmten Sendungen sind zu richten an: 

 Redaction des Botanischen Centralblattes, Haarlem (Holland), Spaarneiy. 



Jesson, E. M., On the Hairs ofthe Tomentum and Ovary 

 in Rhododendron Falconeri, Hock, f., Sind Rhododendron Hodgsoni, 

 Hock. f. (Ann. Bot. XXIX. p. 635-638. 1915.) 



In the course of a critical study of these two species, the hairs 

 were examined anatomicaly with the following results: 



The orange-brown, velvety tomentum of the \e?iYes oi Rhododen- 

 dron Falconeri, Hock., f., proves to be made up of peculiar funnel- 

 shaped hairs, with branches one cell in thickness from the upper 

 portion. That of R. Hodgsoni is more scaly, and the individual 

 hairs are saucer-shaped, having a stalk at the centre of the convex 

 surface The broom-shaped, shaggy hair has not been observed on 

 the leaves of R. Falconeri, as described by Breitfeld; but a 

 similar t3'^pe occurs on the ovary of that species. The tomentum 

 of the ovary of R. Falconeri is extremely variable, thus accounting 

 for the discrepancy existing between various descriptions. The 

 ovary is covered by glandulär and stellate hairs, these being found 

 in very different proportions — in some cases either one or the 

 other being entirely absent. The types of hair described have been 

 found to be constant in many specimens examined, even if the 

 amount of tomentum varied. It is therefore to be concluded that 

 they may have value as characters for use in taxonomy. 



Agnes Arber (Cambridge). 



Small» J.» Irritability ofthe Pollenpresentation Mecha- 

 nism in the Compositae. (Ann. Bot. XXXI. p. 261—268. 1917.) 



Irritability in the pollen-presentation mechanism of the Com- 

 positae has been known since the seventeenth Century at least, but, 



Botan. Centralblatt. Band 137. 1918 15 



