. The Canadian field-naturalist. 170 The Canadian Field-Naturalist Vol. 89 Discussion This is the first hybrid proven to involve D. fragrans, ailthough another described by Tryon in 1942 (D. fragrans X intermedia) pre-dated the benefits from cytological and chemical analyses. Also, it was collected on 4 July which meant that the spores were not fully developed and hence the degree of spore abortion was not known. Wagner and Chen (1965), on the basis of measurements of young exospores, concluded that this plant was in reality a narrow form of Dryopteris inter- media. Dryopteris fragrans is a sm
. The Canadian field-naturalist. 170 The Canadian Field-Naturalist Vol. 89 Discussion This is the first hybrid proven to involve D. fragrans, ailthough another described by Tryon in 1942 (D. fragrans X intermedia) pre-dated the benefits from cytological and chemical analyses. Also, it was collected on 4 July which meant that the spores were not fully developed and hence the degree of spore abortion was not known. Wagner and Chen (1965), on the basis of measurements of young exospores, concluded that this plant was in reality a narrow form of Dryopteris inter- media. Dryopteris fragrans is a small subarctic cUff fern of distinctive appearance. Although spe- cies of Dryopteris are well known for their ability to hybridize (Britton 1965; Wagner 1971), it seemed unlikely that D. fragrans would give rise to successful hybrid offsprmg because of the highly specialized ecological niche occupied by this species and its char- acteristics. Superficially D. fragrans appears remote from the large woodferns (eg., D. goldiana (Hook.) Gray) and is noted for being well covered with specialized scales and glands. Also, although diploid, it has very large spores. The presence of large numbers of both D. fragrans and D. marginalis at this location, together with a suitable intermediate habitat, was apparently sufficient to allow hybridization and permit this hybrid to reach its present healthy state (Figure 16).. Figure 16. Dryopteris X algonquinensis at Greenleaf Lake, 24 June, 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 Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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