A significant portion of the life history of Botrychium, the gametophyte and juvenile sporophytes stages, are spent underground. Experiments were conducted to determine the distribution and abundance of underground structures of eight species of Botrychium. Soil samples were collected in a 200 m2 area, sieved through a series of soil sieves and then processed using a centrifugation technique separating out the lighter plant material. The underground distribution of Botrychium is clumped and not regularly distributed. Only 30% of the samples processed contained underground structures. The gametophytes of B. campestre are most abundant followed by B. mormo with 2021 and 700 gametophytes/m2 respectively. B. montanum and B. fennestratum also have relatively high abundances of 580 and 480 gametophytes/m2. B. virginianum and B. gallicomontanum were the least abundant at 70 and 10 gametophytes/m2. B. campestre and B. gallicomontanum both produce vegetative propagule (gemmae) but there was no apparent correlation with this character and abundance of gametophytes underground. The "underground structure bank" is the source of juvenile plants that will eventually emerge and sustain the populations. The underground bank greatly exceeds in number the visible aboveground portion of the population. Its size and health is critical to sustain the aboveground reproductive portion of the population.

Key words: Botrychium, ecology, moonwort, subterranean gametophytes, underground structures