. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE 672. Bartsia L. Homogamous or protogynous humble-bee flowers ; with nectar secreted by a cushion-like swelling applied to the lower side of the base of the ovary, and stored up at the bottom of the flower. Long- and short-styled forms occur sporadically. Anemophily is not excluded at a later stage of anthesis. 2171. B. alpina L. (Ricca, Atti Soc. ital. sc. nat., Milano, xiv, 1871; Herm. Miiller, ' Alpenblumen,' pp. 283-4; Warming, ' Bestovnin
. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. SCROPHULARINEAE 672. Bartsia L. Homogamous or protogynous humble-bee flowers ; with nectar secreted by a cushion-like swelling applied to the lower side of the base of the ovary, and stored up at the bottom of the flower. Long- and short-styled forms occur sporadically. Anemophily is not excluded at a later stage of anthesis. 2171. B. alpina L. (Ricca, Atti Soc. ital. sc. nat., Milano, xiv, 1871; Herm. Miiller, ' Alpenblumen,' pp. 283-4; Warming, ' Bestovningsmaade,' pp. 7-10, Bot. Tids., Kjobenhavn, xviii, 1890, p. 226; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 331 ; Schulz, 'Beitrage,' II, pp. 118-19.)—Ricca and Hermann Miiller state that the flowers of this species are protogynous in the Alps. Their mechanism resembles that of Melampyrum pratense as regards the structure of the corolla, and that of Rhinanthus major as re- c gards the relative posi- tion of stigma and anthers. Self-pollination is therefore impossible in Alpine flowers. The plants observed by Schulz in the Riesen- gebirge were almost always homogamous or feebly protogamous. When the flower opens, the corolla is 12-16 mm. long; it elongates during anthesis to 17-20 mm., while the style elongates but little. In this way the stigma, which at first projects beyond the anthers, is brought into contact with them, so that automatic self- pollination is inevitable. The plants examined by Lindman on the Dovrefjeld bore homogamous flowers, the stigma and anthers of which matured in the bud. In this case, the end of the style protrudes for a variable distance (1-5 mm.) from the corolla. The anthers are generally enclosed in the flower, which is then dependent upon cross-pollination. Sometimes, however, they grow out of the corolla, and the wind transfers the dry, powdery pollen to the stigma. The flowers in Greenland were found by Warming to be feebly protogynous, the
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