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Kretzer, Bidartondo, and coworkers report on specialization in snow plant-fungal relations. The nonphotosynthetic snow plant (Sarcodes sanguinea) associates with a single fungal species from the Rhizopogon ellenae species complex. Further, a tree host (Abies magnifica, Pinaceae) plays a part in this interesting tripartite symbiosis in which the ``victims'' may prosper under the attack of a parasite. (see p. 1778 and 1783 )

Hybridization and secondary chemistry

Colin Orians reviews the literature on the effects of hybridization on host plant secondary chemistry, the mechanisms that generate patterns of variation, and possible consequences of this variation in the ecology and evolution of plant-herbivore interactions. Qualitatively, hybrids may express or lack parental chemicals, and may also produce novel secondary chemicals. Further, he describes five primary factors that contribute to both qualitative and quantitative variation of these important plant constituents. (see p. 1749)

New relationships in the Compositae

Baldwin and Wessa have found molecular phylogenetic evidence for a sister-group relationship between two difficult lineages of uncertain position in the Compositae—the California tarweed/Hawaiian silversword clade (Madiinae) and the medicinal genus Arnica. The results presented in this paper have far-reaching and provocative implications for the interpretation of revolutionary change, especially pertaining to patterns of chromosome numbers and identification of diploids and polyploids. The expansion of this study beyond the Madiinae is leading to new investigations involving the diversification of the Compositae in western North America. (see p. 1890)

Ovule size as an indicator of fertilization

Seavey, Mangels, and Chappel address an important issue commonly faced by workers in plant reproductive biology, namely, the visual estimation of fertilization based on ovule sizes in developing and mature fruits. The authors provide clear experimental data to demonstrate that in Epilobium obcordatum (Onagraceae) such an estimation can lead to serious error. Neither growth nor absolute size of an ovule in Epilobium is indicative of fertilization because ovule enlargement of fertilized and unfertilized ovules is similar. They suggest that the presence of fertilized ovules in an ovary provides a general hormonal stimulus that causes neighboring unfertilized ovules to grow. (see p. 1765)

This Article Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content