Panax trifolium L.
Panax trifolius, Dwarf gensing
Panax trifolius, Dwarf gensing

Photograph by John Pickering

TABLE OF CONTENTS:

Scientific and Common Names:

Taxonomic Classification:

Kingdom Plantae
Division Magnoliophyta
Class Magnoliopsida
Subclass Rosidae
Order Apiales
Family Araliaceae
Tribe Aralieae
Genus Panax
Species Trifolium

Common Names:


dwarf ginseng

ground nut

Identification:

Description of Species:

Panax trifolium is a springtime herb of eastern North America. It grows to a height of 10-20cm. The Panax trifolium perennates from a short underground rhizome that is attached to a small globose root. It contains a flower cluster of tiny dull white flowers. The flowers have five petals and about 2mm wide. These flowers rise above a whorl of three compound leaves. The leaves are ovate leaflets about 2.5-3.8 cm long. The edge of the leaf is toothed. The fruit of the Panax trifolium is a cluster of yellowish berries. The root is a round white tuberous root (Niering 1995).
Panax trifolium has a very uncommon form of polygamy called androdioecious. There are two forms of the flower, one is the staminate and the other is the hermaphroditic. The staminate and hermaphoditic flowers occur on separate plants.
"The pollen grains of the Panax trifolium are radially symmetrical, isopolor, and tricoloporoidate, with three long, narrow colpi reaching nearly to the poles" (Philbrook 1983). The pollen grains are similar for the two flowers but the mean polar axis lengths are significantly different. The polar axis from the hermaphroditic flower grains have a slightly longer polar axis lengths on the average (Philbrook 1983).
The seeds of the Panax trifolium are white and somewhat reniform in shape. The length of the seed ranges from 2.5mm-3.5mm and the width is 1.5-2.5mm (Niering 1995). The seed is characterized by reticulate network of ridges. From these ridges rises many stiff unicellular hairs. The hairs do not seem to aid in dispersal of the seed.
The morphology of the Panax trifolium flower has two distinct types. One produces morphologically and functional staminate flowers. These have five anthers as well as a single short style, but lack and noticable ovary. The other form is the hermaphroditic flower. This one possess on three carpellate ovary, each carpel capable of producing a single seed. These flowers also contain the full five anther complement (Philbrook 1983).
STAMINATE FLOWER VS. HERMAPHRODITIC FLOWER:
Information from Journal article by Philbrook (1983), see references below.
Staminate Flower: Subconical floral tube surrounds a persistent, reduced, solitary style.
Hermaphroditic Flower: Cylindrical floral tube fused below to three carpellate inferior ovary which is noticably swollen at its base. Three styles arise from top of the ovary.
Both Flowers: Five sepals and five petals alternate on lip of the floral tube. Five two called anthers arise from margin of floral tube opposite sepals.

Reference Where it is Described:

Niering, William A. and Nancy C Olmstead. National Audubon Society Field Guide to North American Wildflowers. New York: Chantieleer Press, 1995.

Philbrick, Thomas C. "Contributions to the Reproductive Biology of Panax trifolium L. (Araliaceae). Rhodora. 77:9 (1983): 97-111.

Authority Who Described the Species:

Carl von Linnaeus (1701-1778)


Scientific Reference which includes the Species within the Identification Key:


Radford, Albert, Harry Ahles and C. Richie Bell. Manual of Vascular Flora of the Carolinas. Chapel Hill: University of North Carolina Press, 1968.

Panax trifolium: Leaflets 3, sessile; tuberous root, round

Holotype and Paratype Specimans and Where the Specimans were Collected:
Could not find this information. I searched a couple of different online Herbariums. I started with the Linneaus collection in the Swedish museum of Natural History, but my species was not there. I was just unable to locate this particular item.

Geography

Overview of Speciman Distribution:

"The Panax trifolium is found in the eastern deciduous forest. From Southern Quebec to Nova Scotia; New England south through mountians to Georgia; west through Indiana to Nebraska and Minnesota (Niering 1995)."

Panax trifolium L.
AREA STATUS REFERENCES
North America:
Continental United States; Canada		Yes Niering and Olmstead 1995;
www.csdl.tamu.edu/FLORA/
Eastern North America:
United States;
Southern Quebec to Nova Scotia Canada		YesNiering and Olmstead 1995;
Philbrick 1983
Southeastern United States:
CT DE GA KY IN MA MD ME MI MN NC NJ NH NY OH PA RI TN VA VT WI WV		YesUS Department
of Agriculture
Southern Appalachian States:
GA KY MD NC TN VA WV		YesUS Department
of Agriculture
Coastal PlainNowww.metalab.unc.edu
PiedmontYeswww.metalab.unc.edu
Blue Ridge MountainsYeswww.metalab.unc.edu;
Niering and Olmstead 1995
Great Smoky Mountains National Park
Yeswww.metalab.unc.edu;
Niering and Olmstead 1995
Ridge and ValleyNoNiering and Olmstead 1995;
Schlessman 1996
Cumberland PlateauNoNiering and Olmstead 1995;
Schlessman 1996
GeorgiaYesUGA Herbarium Specimans
Clarke County, GeorgiaNoUGA Herbarium



Check Out the US distribution of Panax trifolium

Natural History

The Sex Changing Dwarf Ginseng:

The Panax trifolium is a unique and interesting herb due to its ability to change sexs. It can alternate between two different forms. The one phase has the staminate flowers and the other has hermaphoditic flowers. In this rare sexual selection the two phases are environmentally determined(Schlessman 1990). Overseasons, an individual may change gender in either direction and switch gender several times (Schlessman 1996).
The Dwarf Ginseng is a cosexual, nonclonal, spring ephemeral herb of the eastern decidous forest (Schlessman 1996). It has three different distinguishable growth phases. The smallest individuals produce leaves but no flowers, these plants are vegetative. The larger plants are males with staminate flowers, and the largest are hermaphrodites with hermaphroditic flowers. "From year to year on fourth to one third of the reproductive individuals change phase from male to hermaphrodite or hermaphrodite to male (Schlessman 1990)."
The seeds of the Panax trifolium are dispersed by gravity(Meier 1995). They fall to the ground and filter themselves into leafs and soil. The seeds germinate the following spring after they are shed. The seed coat falls off about late Fall, not just before germination (Philbrook 1983). The slow rates of dispersal of the seeds from the parental plants make many landscape features a challenge for the dwarf ginseng plant. Features such as high elevations, dry ridges, and agricultural fields would be expected to present impassible barriers for these plants (Meier 1995).
The Dwarf Ginseng is self compatible. Both gender phases have viable pollen. Both plants are capable of effecting fertilization. Males produce more flowers than hermaphrodites, two to three times more. They also produce more pollen per anther, about 1.2 times more viable pollen (Schlessman 1996). The dwarf ginseng plant is pollinated by small solitary bees and by flies. Although the plant is genetically self compatible, self pollinization is prevented by strong intra and interfloral protandry (Schlessman 1996).
"The phenotypic gender of hermaphrodites is extremely female biased; it is likely that hermaphrodites function essentially as females" (Schlessman 1990). The view that the hermaphroditic phase is functionally female is supported by two things. One is the period of pollen presentation by hermaphrodites. It is shorter than receptive stigma presentation. "Second the relatively strong synchrony of flowering among hermaphrodites produce only a small amount of overlap among the pollen presenting and stigma presenting stages of different hermaphrodite plants" (Schlessman 1996). In effect a large proportion of the hermaphrodites pollen appears to be prevented from reaching receptive stigmas because it is presented too soon.
There are two main phenological differences between the two different forms of the Panax trifolium plants. First the presentation of pollen by males coincides closely with stigma presentation, but is significantly different from the pollen presentation by hermaphrodites. The other difference is that males present pollen longer than hermaphrodites. This strongly suggests that male-male competition has been a force in the evolution of the floral phenology of the dwarf ginseng.
One alternative to the male-male competition theory is "larger inflorescences of males might be a proximate physiological consequence of their lower reproductive effort" (Schlessman 1996). Gender change is common and frequent. Individuals that are in the male phase will at some point in the future will have to incur the costs of maternal function, or they may have incurred them in the past. The resource cost of maternal function is greater than the costs of paternal function. Three lines of evidence support this view. First is males are smaller than hermaphrodites. Second the reproductive effort of hermaphrodites is much longer. And finally in the year following fruit production a plant is much more likely to have become smaller and change gender to male, rather than grow larger and remain hermaphroditic (Schlessman 1996).

How to Locate

Where and When to Find Panax trifolium :

Panax trifolium can be found in the eastern part of the US and Canada. It is a perrineal springtime herb of the eastern deciduous forest. The dwarf ginseng plant requires a moist humus rich soil in a shady position in a woodland. The plant has leaves above the ground for only two months each year (www.metalab.unc.edu). The flowers can be seen in April-June (Niering 1995).

Images

Does the Panax trifolium intrigue you?!
Would you like to see more of the dwarf ginseng plant?!
Below are links to more photographs of this stunning speciman!

References


Meier, Albert J. Susan Power Bratton and David Cameron Duffy. "Possible Ecological Mechanisms for Loss of Vernel-Herb Diversity in Logged Eastern Decidous Forests." Ecological Applications. 5:4 (1995): 935-946.

Maout and Decaisne. System of Botany. London: Logman, Green, Reader, and Dyer, 1873.
Niering, William A. and Nancy C Olmstead. National Audubon Society Field Guide to North American Wildflowers. New York: Chantieleer Press, 1995.

Philbrick, Thomas C. "Contributions to the Reproductive Biology of Panax trifolium L. (Araliaceae). Rhodora. 77:9 (1983): 97-111.

Radford, Albert, Harry Ahles and C. Richie Bell. Manual of Vascular Flora of the Carolinas. Chapel Hill: University of North Carolina Press, 1968.

Schlessman, Mark A. "Phenotypic Gender in Sex Changing Dwarf Ginseng, Panax trifolium (Araliaceae)." American Journal of Botany. 77:9 (1990): 1125-1131.

Schlessman, Mark A., Nora C. Underwood and Laura M. Graceffa. "Floral Phenology of Sex Changing Dwarf Ginseng (Panax trifolium L., Araliaceae)." Ecological Applications. 5:4 (1995): 935-946.

Web Pages:

http://www.csdl.tamu.edu/FLORA/
http://www.cce.cornell.edu/oswego/4-H/amboy/wildflowers/panax.htm
http://www.albion.edu/fac/biol/skean/panatrpg.htm
http://faculty.vassar.edu/~schlessm/Ptrifolium.html
http://chili.rt66.com/hrbmoore/NGSImages/Panax_trifolium.jpg
http://www.metalab.unc.edu/pfaf/egi_bin/arr_html?Panax+trilolius
http://django.harvard.edu http://plants.usda.gov/plantproj/ http://www.itis.usda.gov/plantproj/itis/




Amy Todd
University of Georgia
General Ecology Student May 1999
atodd@arches.uga.edu