HELIOTROPISM
\hˈɛlɪˌɒtɹə͡ʊpˌɪzəm], \hˈɛlɪˌɒtɹəʊpˌɪzəm], \h_ˈɛ_l_ɪ__ˌɒ_t_ɹ_əʊ_p_ˌɪ_z_ə_m]\
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The directional growth of organisms in response to gravity. In plants, the main root is positively gravitropic (growing downwards) and a main stem is negatively gravitropic (growing upwards), irrespective of the positions in which they are placed. Plant gravitropism is thought to be controlled by auxin (AUXINS), a plant growth substance. (From Concise Dictionary of Biology, 1990)
By DataStellar Co., Ltd
Word of the day
basidiomycota
- comprises fungi bearing the spores on basidium: Gasteromycetes (puffballs); Tiliomycetes (comprising orders Ustilaginales (smuts) and Uredinales (rusts)); Hymenomycetes (mushrooms; toadstools; agarics; bracket fungi); in some classification systems considered a division of kingdom comprises fungi bearing spores on a basidium; includes Gasteromycetes (puffballs) Tiliomycetes comprising the orders Ustilaginales (smuts) and Uredinales (rusts) Hymenomycetes (mushrooms, toadstools, agarics bracket fungi).