88 L e w , The iiectaiy and the sterile stamen of Pentastemon etc. 



with ternatus, P. breinflorus witli anfirrhinoides and P. BotJi- 

 rockii witli Lemmoni seem to liave the most similar featnres of 

 flower-structure. 



From tliese preliminary and very incomplete obser\rations 

 I conclude that the formation of nectaries is not the same 

 in the different species of Poitasfemon and that there is in 

 the Fruticosi group a very interesting divergence, in which also 

 the staminodium is involved as serving with its dilated and 

 bristly base as a honey protecting organ. The same function 

 is assigned also to the base of the four iilaments. All this seems 

 to explain the fundamental ecological function''') of the sterile 

 stamen, so much disputed tili now. 



If my notion of the flower-structure in the Fruticosi group 

 is right, we should have in the genus Pentastemon two different 

 branches, the one with staminal glands and without honey- 

 protecting organs at the base of the filaments, the other with 

 this kind of organs, yet with a divergent mode of honey- 

 secretion. 



The true mode of honey-secretion, howewer, in flowers of 

 the Fruticosi is unknown tili to-day and I have been unable to 

 settle the question by means of herbarium-specimens or otherwise. 

 Therefore 1 address to American botanists, who have opportu- 

 nities for observing any species of the Fruticosi in living Cali- 

 fornian plants the request kindly to complete my observations. 



5) See Errera, L. et Grevaert, -q. Bull. Soc. Roy. Bot. Belgiqiie 

 17:182—248. 1878. — Kerner, A. Die Soliutzmittel der Blüten gegen un- 

 berufene Gäste. Wien 1876:55. — Loew, E. Blüteubiol. Beitr. Pringsli. 

 Jahrb. 22:475-485. 1891. — Pasquale, F. Süll, impollinaz. nel Penst. 

 gentianoides, Atti del congr. internaz. di Genova 1892 : 553 — 560. 



