n6 ANGIOSPERMAE—DICOTYLEDONES 



Many forms limit access to their nectar entirely or almost so to bees. e. g.- 

 Pulmonaria by elongation of the corolla-tube ; Anchusa by closure of the entrance to 

 the flower ; Echium by the form of the corolla ; Borago by torsion of the fiowers, 

 and apposition of the anthers into a cone closing their entrance ; Symphytum and 

 Cerinthe by elongation of the corolla-tube in addition to this. The species with 

 shorter corolla-tubes from the genera Myosotis, Omphalodes, Echinospermum, 

 Asperugo, Heliotropium, Lithospermum, and Cynoglossum, are visited by bees, 

 Lepidoptera, and flies, more especially by hover-flies. 



According to Kuhn (Bot. Ztg., Leipzig, x.xv, 1867), species of the genera 

 Amsickia, Eritrichium, Hockinia, and Lithospermum, are dimorphous. Darwin 

 ('Different Forms of Flowers'), however, denies that this is the case in the first two 

 of these, there being simply a large amount of variation in the length of the stj'les 

 and stamens. 



595. Heliotropium L. 



Flowers fragrant, short-tubed, and homogamous ; with very scanty or no 

 secretion of nectar. 



1953. H. europaeum L. (Kirchner, ' Beitrage,' pp. 49-50.) — The small 

 insignificant flowers of this species are homogamous, and their odour is compared 

 by Kerner to that of vanilla, by Delpino to that of jessamine. The limb of the 

 corolla is 3-3^ mm. across, its throat is of a yellow colour, and its tube (2 mm. long) 

 is entirely surrounded by the calyx. The yellow anthers are produced into points, 

 and situated in the middle of the corolla-tube. The style projects beyond them, and 

 bifurcates at its end into the pointed stigmas, which mature simultaneously with the 

 anthers. During insect-visits crossing is therefore favoured, but these are infrequent. 

 Kirchner was unable to discover any nectar in flowers from canton Valais. 



1954. H- peruvianum L. (Sprengel, ' Entd. Geh.,' p. 87; Knuth, 'Bloe- 

 menbiol. Bijdragen.') — The bluish-white homogamous flowers of this species smell 

 like vanilla. 



Visitors. — The following were recorded by the observers, and for the localities 

 stated.— 



Knuth (gardens in Kiel), the honey-bee, freq., inserting its proboscis into the 

 base of the flowers ; also the Muscid Calliphora vomitoria L., skg. Errera and 

 (Jevaert, butterflies and the diurnal hawk-moth Macroglossa stellatarum L. 



596. Asperugo L. 



Flowers homogamous ; with concealed nectar, secreted by the receptacle 

 immediately below the ovary. 



1955. A. procumbens L. (Kirchner, ' Beitrage,' p. 50 ; Knuih, ' Flora v. 

 Helgoland.') — At Zermatt the inconspicuous flowers of this species are borne singly 

 in the leaf-axils, and possess a corolla-tube scarcely 2 mm. long, with a dark-brown 

 corolla limb and a violet ring in the throat. The entrance of the corolla-tube is 

 narrowed by five whitish projections, formed by inpushings from the outside. The 

 corolla-limb is generally directed obliquely upwards and is then only 3 mm. in 

 diameter; more rarely it is horizontal, in which case it is 5 mm. across. 



