Exploring the science of plants, from the field to the lab

In Search of Fumewort at Garth Woods, We Found Something Better

Posted in From the Field on July 7, 2016 by Science Talk

Laura Booth and Zihao Wang are Forest Interns at The New York Botanical Garden.

Abundant and diverse herbaceous layer in Garth Woods
Abundant and diverse herbaceous layer in Garth Woods

On a steamy day in late May, a crew of invasive species scouts assembled in the parking lot of the Garth Woods Apartments in Scarsdale, Westchester County. Our mission? To survey Garth Woods, a sliver of intact riparian forest, for Corydalis incisa, also called incised fumewort or purple keman. Much to our excitement, this case of sleuthing had a happy ending: for now, Garth Woods shows no sign of C. incisa, and full to the brim with uncommon native herbs that were a joy to see.

C. incisa, which is native to Asia, is an emerging invasive along the Bronx River; it was first recorded in the New York metropolitan region during the Bronx Park BioBlitz in 2005, and has subsequently been observed along the riverbanks of the Bronx River in The New York Botanical Garden and in several sites in Westchester County.

Where possible, proactively addressing the spread of aggressive invasive plants—including incised fumewort—is an important facet of natural resource management. As newcomers to the ecosystems in which they are introduced, invasive species frequently lack predators and can outcompete native species, threatening the intricate functioning of ecosystems. Now, through a partnership between the Bronx River Alliance and affiliates, the Lower Hudson Partnership for Regional Invasive Species Management, New York City Parks, and The New York Botanical Garden, community members and botanists are working together to systematically survey sites along the Bronx River for C. incisa populations.

Garth Woods, a charming, 60-acre remnant of old-growth forest wedged between the north- and southbound Bronx River Parkway from Harney Road to Crane Road, is one such survey site. We joined Jessica Schuler, Director of the Thain Family Forest; and Bob DelTorto and Suzanne Nolan, volunteers from the Bronx River Parkway Reservation Conservancy in laying a 100-meter transect, along which we began actively looking for C. incisa. This species’ diminutive size, delicate and highly divided leaves, and dusky purple flowers belie its violent spreading mechanism: an explosively dehiscent green fruit that can send seeds up to nine feet from the parent plant.

Veratrum viride and Hedera helix
Veratrum viride and Hedera helix

But as we scanned the shady forest floor, dappled with the special light of mid-afternoon in late spring, we discovered delight after delight, without the scar of a single C. incisa plant. Among our finds were golden Alexander, Zizia aurea, a flowering perennial herb, just turning the color of its common name; blue cohosh, Caulophyllum thalictroides, without its blue fruits, but making itself known by its characteristic “tulip-shaped” leaves; and wild ginger growing in secretive patches, concealing their ethereal maroon flowers. When Jessica stumbled across a Veratrum viride, or false hellebore, her enthusiasm was audible: this highly toxic plant is one of her favorite herbs! Other especially nice finds included cutleaf toothwort, Cardamine concatenata; bloodroot, Sanguinaria canadensis; and wake robin, Trillium erectum. You can find a full list of the 66 species we encountered at Garth Woods, prepared by Zihao Wang, at the bottom of this post.

ISAWWhy has Garth Woods, an unassuming fragment of forest situated between strips of a very busy highway, retained so much of its understory biodiversity in comparison to other local forests? We can’t say for sure, but one contributing factor may be the absence of deer in this isolated spot. The presence of the highway on either side of the Woods acts as a barrier, preventing high concentrations of deer from stripping the herbaceous and shrub layers of their native species, which would open them up to colonization by invasives. Many other variables are likely acting simultaneously to produce this lovely example of native Northeastern biodiversity.

To report information about Corydalis incisa, please contact datha@nybg.org. New York is celebrating its third annual Invasive Species Awareness Week July 10–16, 2016! Learn more about events and activities here.


Genus Species Native Status Type Common Names
Ambrosia trifida Native Herb Giant Ragweed
Aralia nudicaulis Native Herb Wild Sarsaparilla
Asarum canadense Native Herb Wild Ginger
Bidens frondosa Native Herb Devil’s Beggartick
Cardamine diphylla Native Herb Crinkleroot
Cardamine concatenata Native Herb Cutleaf Toothwort
Caulophyllum thalictroides Native Herb Blue Cohosh
Cryptotaenia canadensis Native Herb Honewort
Epifagus virginiana Native Herb Beechdrop
Erythronium americana Native Herb Troutlily
Hydrophyllum virginianum Native Herb Virginia Waterleaf
Impatiens capensis Native Herb Jewelweed
Laportea canadensis Native Herb Wood Nettle
Maianthemum racemosum Native Herb False Solomon’s Seal
Onoclea sensibilis Native Herb Sensitive Fern
Polygonatum pubescens Native Herb Solomon’s Seal
Polystichum acrostichoides Native Herb Christmas Fern
Sanguinaria canadensis Native Herb Bloodroot
Solidago flexicaulis Native Herb Zigzag Goldenrod
Symplocarpus foetidus Native Herb Skunk Cabbage
Thalictrum dioicum Native Herb Meadow Rue
Trillium erectum Native Herb Wake Robin
Veratrum viride Native Herb False Hellebore
Viola sororia Native Herb Common Violet
Viola striata Native Herb Striped Cream Violet
Zizia aurea Native Herb Golden Alexander
Alliaria petiolata Non-native Herb Garlic Mustard
Artemisia vulgaris Non-native Herb Mugwort
Cardamine impatiens Non-native Herb Narrowleaf Bittercress
Lepidium didymum Non-native Herb Lesser Swinecress
Ranunculus ficaria Non-native Herb Lesser Celandine
Reynoutria japonica Non-native Herb Japanese Knotweed
Reynoutria x bohemica Non-native Herb Japanese Knotweed
Lindera benzoin Native Shrub Spicebush
Ribes sp. Native? Shrub Currant
Berberis thunbergii Non-native Shrub Japanese Barberry
Euonymus alatus Non-native Shrub Burning Bush
Rhodotypos scandens Non-native Shrub Jetbead
Rosa multiflora Non-native Shrub Multiflora Rose
Viburnum dilatatum Non-native Shrub Linden Viburnum
Viburnum sieboldii Non-native Shrub Siebold Viburnum
Viburnum plicatum Non-native Shrub Doublefile Viburnum
Acer negundo Native Tree Boxelder
Acer saccharinum Native Tree Silver Maple
Acer rubrum Native Tree Red Maple
Acer saccharum Native Tree Sugar Maple
Carpinus caroliniana Native Tree Ironwood
Carya ovata Native Tree Shagbark
Fagus grandifolia Native Tree American Beech
Fraxinus pennsylvanica Native Tree Green Ash
Liriodendron tulipifera Native Tree Tulip Tree
Populus deltoides Native Tree Eastern Cottonwood
Prunus serotina Native Tree Blackcherry
Quercus rubra Native Tree Red Oak
Tilia americana Native Tree Basswood
Ulmus americana Native Tree American Elm
Acer platanoides Non-native Tree Norway Maple
Acer palmatum Non-native Tree Japanese Maple
Kalopanax septemlobus Non-native Tree Castor Aralia
Echinocystis lobata Native Vine Wild Cucumber
Parthenocissus quinquefolia Native Vine Virginia Creeper
Toxicodendron radicans Native Vine Poison Ivy
Celastrus orbiculatus Non-native Vine Oriental Bittersweet
Hedera helix Non-native Vine English Ivy