Botrychium is a genus of ferns, seedless vascular plants in the family Ophioglossaceae. Botrychium species are known as moonworts. They are small, with fleshy roots, and reproduce by spores shed into the air. One part of the leaf, the trophophore, is sterile and fernlike; the other, the sporophore, is fertile and carries the clusters of sporangia or spore cases. Some species only occasionally emerge above ground and gain most of their nourishment from an association with mycorrhizal fungi. The circumscription of Botrychium is disputed between different authors; some botanists include the genera Botrypus and Sceptridium within Botrychium, while others treat them as distinct. The latter treatment is provisionally followed here.
The rattlesnake fern has traditionally been placed in the Botrychium subgenus Osmundopteris, the name of which is based on the species' superficial similarities to the genus Osmunda where it was previously placed.
These species have traditionally been placed in the Botrychium subgenus Sceptridium,a name based on the apparent similarity of their sporangia to "little scepters."
Botrychium rugulosum – St. Lawrence grape fern, Rugulose grape fern, Ternate grape fern
Botrychium schaffneri –
Botrychium subbifoliatum – Island grapefern
= Sceptridium subbifoliatum
Botrychium underwoodianum
Conservation
Moonworts can be found in many environments, including prairies, forests, and mountains. While some Botrychium species are quite rare, conservation efforts can be difficult. Determining the rarity of a species is complicated by the plants’ small leaves, which stand only 2-10 centimeters above the soil. Even more of a challenge in obtaining an accurate population count is the genus’s largely subterranean life cycle. The vast majority of any one population of moonworts actually exists below ground in banks consisting of several types of propagules. One type of propagule is the ungerminated spores, which must percolate through the soil beyond the reach of light in order to germinate. This presumably increases the probability that the spore will be in range of a mycorrhizal symbiont before it produces the tiny, roughly heart-shaped gametophyte, which also exists entirely below ground. Finally, some species produce gemmae, a form of asexual propagation achieved by budding of the root. Juvenile and dormant sporophytes can also be hidden in the soil for long periods of time. Mature sporophytes do not necessarily produce a leaf annually; they can remain viable underground for up to 10 years without putting up a photosynthetic component. This feat is made possible by their dependence on symbiotic partnership with AM fungi of the genus Glomus, which supply most fixed carbon for growth and reproduction. This mycorrhizal dependence has also made lab cultivation of moonworts difficult. Thus far, only germination of the gametophyte has been successful.
