Dennstaedtia punctilobula is a fern to 80 cm tall, from a slender, rapidly growing, branching rhizome, new growth can also arise from buds on frond stalks (Hammen 1993), aggressively colonial;
Leaves arising singly along rhizome; stalk to 20 cm long, dark reddish-brown, pale above, stalks and midribs hairy; blade to 25 cm wide, fragrant, feathery, twice pinnate, often hairy, leaflets 17-25 per side, to 13 cm long, 4.5 cm wide, ultimate leaflets stalkless, deeply lobed and toothed, matte yellow-green, soft, basal leaflets only slightly smaller than those in middle.
Spore cases round, along leaflet margins, at tips of some veins, spores mature Aug.-Sept.
Wetland status: UPL.
Frequency in NYC: Frequent.
Habitat: Open, upland areas or bright woodland understory. Often in burned-over sites. Tolerates soil acidity down to pH 4.0 (Greller et al. 1990). Found forest in soil pH 4.8-5.0 (Gargiullo unpublished data).
Notes: Apparently can exclude other herbs and retard establishment of tree seedlings (Horsley and Marquis 1983). Very similar in appearance to New York fern (Thelypteris noveboracensis), which is also aggressively colonial (see below). Roots associated with vesicular-arbuscular endomycorrhizal fungi (Berliner and Torrey 1989); in spring, fronds expand before canopy closure increasing growth when light is brightest (Hammen 1993).