452 ANGIOSPERMAE—DICOTYLEDONES 



1069. C. intermedia Ehrh.— 



Visitors. — These are the same hover-flies as in C. alpina. This lends suppoii 

 to the view that this species is a hybrid between C. lutetiana and C. alpina which 

 has become fixed. Loew saw Thrips in the Berlin Botanic Garden. 



305. Isnardia L. 



1070. I. palustris L. (=Ludwigia palustris Z.). — In this species, according 

 to Vaucher ('Hist, physiolog. des pi. d'Europe,' II, p. 338), the anthers of the green 

 inconspicuous flowers are inclined towards the stigma at the beginning of anlhesis, 

 and the shrivelled anthers together with the style soon fall off'. Monoecious stocks 

 also occur (var. paludosa Rabenhorst). 



306. Gaura L. 



1071. G. biennis L. — 



Visitors. — Loew observed the following in the Berhn Botanic Garden. — 



A. Diptera. Syrphidae : i. Syrphus ribesii Z., po-dvg. B. Hymeno- 



ptera. {a) Apidae: 2, Apis mellifica Z. 5, po-cltg. {b) Vespidae: 3. Odynenis 



parietum Z., var. renimacula Lep. 5. 



307. Fuchsia L. 



1072. F. sp. — Gaertner states that the species of Fuchsia are self-fertile. — 

 Visitors. — Schneider records the humble-bees Bombus pratorum Z. 5 and B. 



terrester Z. 5 for gardens in Arctic Norway (Mus. Aars. Troms0, 1894). 



308. Trapa L. 



Small inconspicuous whitish flowers. Caspary describes the nectary as a 

 glandular ring surrounding the middle of the ovary (' De nectariis '). 



1073. T. natans L. — For plants of this species living in Lake Maggiore 

 Gibelli and Buscalioni determined that anthesis extends from the end of June to 

 ilie beginning of September, reaching its maximum in August. The flowers normally 

 expand an hour or half an hour before sunrise, and remain open only a few hours. 

 On warm and dry days the peduncles begin to curve carpotropically after 5-6 

 hours ; on dull cloudy days this takes place later. The flowers almost always 

 open in the air, rarely under water. Some of the closed submerged ones possess 

 dehisced anthers and pollen-covered stigmas, so that they must be described as 

 hydro-cleistogamous. Usually, however, these flowers open if the plant is taken 

 out of the water. Such opening is effected by the elongating stamens, which press 

 against the petals, and push them apart. The higher temperature of the air also 

 helps to bring this about. After the flowers have opened in the air autogam\- 

 usually follows. 



Visitors. — Gibelli advanced the view in 1891 that pollination is presumably 

 effected by the larvae of the water-bug Mesoveha furcata ]\[uls ei Rey, but he and 

 Buscalioni subsequently (1893) came to the conclusion that the presence of the 

 larvae in the flowers is merely accidental, for these little creatures are not in the 

 smallest degree adajited to the mechanism. Nor did these observers regard 



