BORAGINEAE 119 



602. Caccinia Savi. 



1964. C. strigosa Boiss. (Loew, Ber. D. bot. Ges., iv, 1886, pp. 164-6.) 

 The corolla-tube of this species is 14 mm. long and 2^ mm. broad. The five 

 stamens are of various lengths ; one of them is as long as the widely exserted style, 

 two are about 2 mm. shorter than this, and the remaining two are still shorter. Since 

 the four latter stamens dehisce first, autogamy is excluded to begin with, and crossing 

 by insect-visits favoured. Should these fail, automatic self-pollination can ultimately 

 take place when the long stamen dehisces. 



^'isiTORS. Loew observed the humble-bee Bombus hortorum Z. in the Berlin 

 Botanic Garden, skg., and dusting its under-side with pollen. 



603. Arnebia Forsk. 



1965. A. echioides A. DC. (=Macrotomia echioides Boiss.). (Loew, op. cit., 

 iv, 1886, pp. 164-6.) This species is particularly interesting because the dark-violet 

 spots on the corolla serving as nectar-guides gradually disappear after one to three 

 days' anthesis, i. e. the ' nectar signals ' are temporary, and exist only on the younger 

 flowers. 



As the nectar is very deeply concealed, besides which Loew observed the 

 humble-bee Bombus hortorum L., skg., the flowers may be referred to flower 

 class Hh. 



Loew describes a long-styled plant from the Berlin Botanic Garden as 

 exhibiting much reduced fertility, but not self-sterile. 



Visitors. Vide supra. 



604. Trachystemon D. Don. 



1966. T. orientale D. Don (=Psilostemon orientale DC). (Loew, op. cit., iv, 

 1886, pp. 155-7.) The flowers of this species possibly belong to class L. 



605. Borago L. 



Protandrous bee flowers ; with nectar secreted by the receptacle below the 

 ovary, and concealed in a short tube formed by the roots of the filaments. 



1967. B. officinalis L. (Sprengel, 'Entd. Geh.,' pp. 94-8; Herm. Miiller, 

 'Fertilisation,' pp. 409-11, * Weit. Beob.,' Ill, p. 14 ; Kirchner, ' Flora v. Stuttgart, 

 PP- 554-5; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 275.) The sky-blue 

 hanging flowers expand so as to present a nearly flat surface, from the centre 

 of which the black cone of anthers projects. The anthers which converge to 

 make up this cone dehisce introrsely from apex to base, and the smooth powdery 

 pollen falls into the end of the cone. This surrounds the style with its stigma, 

 but as the latter is still immature automatic self-pollination is excluded. After 

 nectar-sucking insects have removed the pollen from the cone the style grows out 

 of it, and the stigma matures. Only bees are able to open the flowers. When 

 one of these hangs on from below to a flower in the first stage of anthesis, and 

 probes for nectar, its proboscis must be inserted between two filaments, thus 



