| 释义 |
geotropism Bot.|dʒiːˈɒtrəpɪz(ə)m|
[f. as prec. + -ism. First used in Ger. form geotropismus by A. B. Frank Beitr. z. Pflanzenphysiol. (1868).]
A collective term for the phenomena of irritability presented by various parts of plants in relation to the action of gravity. positive geotropism: the tendency (of roots, etc.) to grow towards the centre of the earth. negative g..: the tendency (of stems, etc.) to grow away from the centre of the earth.
By C. and F. Darwin (1880) the word was used in a narrower sense, as synonymous with the ‘positive geotropism’ of other writers, the term apogeotropism being substituted for ‘negative geotropism’. diageotropism, the tendency (of leaves) to grow at right angles to the vertical, is a third variety of ‘geotropism’ in the original (and still prevalent) wider sense of the word.
1875Bennett & Dyer Sachs' Bot. 758 The positive or negative character of geotropism depends as little as that of heliotropism on the morphological nature of the organ. 1880F. Darwin in Nature XXXIII. 179 The phenomena might result from the ordinary forms of heliotropism and geotropism acting in concert.
So also geˈotropy.
1889in Century Dict. |