Cut-leaf grape fern is a perennial, evergreen fern with a single, two-parted leaf that arises from the ground with what looks like two separate stalks into a vegetative portion and a fertile portion. The blade of the vegetative (leafy) portion is leathery, broadly triangular in outline, and fernlike, 2–4 times pinnately compound. It usually curves back so that it’s nearly horizontal to the ground. The fertile (spore-bearing) portion splits away at the lower one-third of the shared stalk (at a glance it may appear as a separate stalk); at the top of its erect stalk, it has a 2–3 times pinnately compound cluster of rounded spore-bearing structures (hence the name “grape fern”). Spores are released August–November.
Leaves are produced in early summer, and they turn a reddish bronze color before overwintering. The previous season’s leaves usually wither when new leaves develop in late spring.
Two close relatives occur in Missouri:
- Sparse-lobed grape fern, Botrychium biternatum, is rare in Missouri and restricted to the Mississippi Lowlands of the Bootheel. It is closely related to cut-leaf grape fern. Its vegetative leaves, however, are thin-textured (not leathery), and they are only 2–3 times pinnately compound (not 2–4 times). They usually don’t change color prior to overwintering. Sometimes experts have trouble telling them apart.
- Rattlesnake fern, Botrypus virginianus (syn. Botrychium virginianum), is common throughout Missouri. It differs from the above two by having the leaf divided higher up on the shared stem. The stem diverges into vegetative and fertile portions well above the ground, and the fernlike vegetative portion is sessile (stalkless). It is the commonest grape fern in Missouri.
Finally, another relative, prairie moonwort, Botrychium campestre, could someday be found in the loess hill prairies of northwestern Missouri. It occurs very nearby in southwestern Iowa. A tiny plant, it is usually less than 2½ inches tall, so it is difficult to find among the dense prairie vegetation where it grows.
Habitat and Conservation
Humans are experts at language, and the rich vocabulary used to describe the various anatomical features of ferns is a great example of how learning new words helps us learn concepts, and learning concepts facilitates learning new words.
There are precise names for the two portions of a grape fern leaf: the vegetative (leafy) portion is called a trophophore, and the fertile (spore-producing) portion is called a sporophore. The words have Greek roots. The “troph-” of trophophore refers to nutrition (because the leaves conduct photosynthesis, which makes food for the plant). The “-phore” part of the word means “carrier” or “bearer.” Now that you know this, you can figure out what sporophore means!
The genus name Botrychium comes from the Greek word botrys (a bunch of grapes). It refers to the spore cases that look like clusters of tiny grapes.
This fern is rarely cultivated, mostly because it is difficult to propagate. Its reliance on soil-living symbiotic fungi makes it difficult or impossible to transplant successfully. Please enjoy these interesting ferns in their natural habitat.
Deer, wild turkey, and other animals eat the foliage of cut-leaf grape fern, especially in spring and fall, when these evergreen plants are most noticeable.
The plant’s succulent foliage, combined with remarkably thick walls on the spores, could be clues that this fern might be dispersed by the animals that eat it. The thick-walled spores can potentially survive the trip through a mammal’s digestive tract and be deposited away from the parent plant.
Studies have suggested that cut-leaf grape fern derives most of its nutrition from mycorrhizal (fungal) connections with its roots. In fact, photosynthesis may be only secondarily important as a source of food. This means that when browsing animals chew off the leaves of this fern, it may not cause a dire reduction in nutrition for the plant.
The success of grape ferns is tied to the destiny of its fungal partners. Anything that harms the fungi needed by grape ferns will also harm the grape ferns. Some factors that can impact the fungi’s survival include timber harvesting, road building and other construction, land use changes that affect the drainage and moisture in the soil, and the presence of nonnative (European) earthworms, which change the historic structure of the soil, the amount of leaf litter, and the soil nutrient cycles.