. Plant studies; an elementary botany. Botany. 136 PLANT STUDIES the unsuitable insects, which Kerner calls " unbidden guests," are ants, and adaptations for reducing their visits to a minimum may be taken as illustrations. (1) Hairs.—A common device for turning back ants, and other creeping insects, is a barrier of hair on the stem, or in the flower cluster, or in the flower. (2) Glandular —In some cases a sticky secretion is exuded from the surface of plants, which effectively stops the smaller creep- ing insects. In certain species of catch-fly a sticky ring girdles ea
. Plant studies; an elementary botany. Botany. 136 PLANT STUDIES the unsuitable insects, which Kerner calls " unbidden guests," are ants, and adaptations for reducing their visits to a minimum may be taken as illustrations. (1) Hairs.—A common device for turning back ants, and other creeping insects, is a barrier of hair on the stem, or in the flower cluster, or in the flower. (2) Glandular —In some cases a sticky secretion is exuded from the surface of plants, which effectively stops the smaller creep- ing insects. In certain species of catch-fly a sticky ring girdles each joint of the stem. (3) Isolation.— The leaves of cer- tain plants form water reservoirs about the stem. To ascend such a stem, therefore, a creeping insect must cross a series of such reservoirs. Teasel furnishes a common illustration, the opposite leaves being united at the base and forming a series of cups. More extensive water reservoirs are found in Bilbergia and Bavenala (" traveler's tree "), whose flower clusters are protected by reservoirs formed by the rosettes of leaves, which creeping insects cannot cross. (4) Latex.—This is a milky secretion found in some plants, as in milkweeds. Caoutchouc is a latex secretion of certain tropical trees. When latex is exposed to the air it stiffens immediately, becoming sticky and finally. Fig. 142. A bee escaping from the pouch of Cypri- pedium, and rubbing against an anther.—After Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
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