Underground gemmae in Botrychium subgenus Botrychium are described as the first report of such structures in ferns. Gemmae are spherical units 0.5–1 mm in diameter produced on the stem, where they originate in meristematic regions of the outer cortex. At maturity they contain an embedded apical cell and may contain a mycorrhizal fungus. Upon abscission from the stem they remain subterranean and may undergo growth and development into completely differentiated sporophytes in a pattern similar to that of development of sexually produced embryos. In addition to the diploid B. campestre, gemmae occur in the tetraploids B. minganense, B. echo, and a new species as yet undescribed. These may be allotetraploids of which B. campestre is one parent. The ecological significance of reproduction by gemmae may lie in the advantages of asexual reproduction in the dry prairie habitat of B. campestre.
Temporal and demographic aspects of the growth of Botrychium gallicomontanum and B. mormo were studied for 2 yr. A total of 219 B. gallicomontanum and 412 B. mormo plants were monitored in a prairie and maple-basswood forest, respectively. Growth events were divided into four stages: leaf emergence, leaf separation, spore release, and senescence. Botrychium gallicomontanum emerged in April, peaked during the first week of June, and declined rapidly. The largest plants were found in late June and early July with a mean peak trophophore size of 4.0 ± 1.8 cm. Botrychium mormo emerged in June, and the population size peaked in early July. The largest plants occurred late in August with a mean peak trophophore size of 3.0 ± 1.1 cm. The mean season span, or period of emergence aboveground annually, for B. gallicomontanum and B. mormo was 7.7 ± 2.4 and 11.9 ± 3.5 wk, respectively. Late-emerging plants produced spores in shorter periods. The separation stage was prolonged in B. gallicomontanum plants, whereas B. mormo plants had a much longer separation stage. Phenological differences are related to different habitat parameters of grassland and forest. Understanding the phenology of these rare species will help us more accurately predict the impact of management practices.
A significant portion of the stages of the life history of Botrychium, the gametophyte and juvenile sporophytes, are spent helowground. Surveys were conducted to determine the distribution and abundance of belowground gametophj^es, juvenile sporophytes and gemmae of
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