Name: Persicaria arifolia (L.) Haraldson
Family: Polygonaceae, the Buckwheat Family
Common Names: Tear-thumb, Halberd-leaf tearthumb
Etymology: ‘Persicaria’ refers to the resemblance of the leaves of members of the genus to the Persian apple tree, or Peach (1,21,22). Arifolia refers to the resemblance of the leaves of this species to Arum leaves, which are shaped like arrowheads (1,2,21).
Botanical synonyms (3,4,5):
Tracaulon arifolium (L.) Rafinesque
T. ruellum arifolium (L.) Soják
Polygonum arifolium L.
Polygonum arifolium v. lentiforme Fernald & Griscom
Polygonum arifolium v. pubescens (R. Keller) Fernald
Quick Notable Features:
¬ Arrow-head shaped leaves
¬ Reversed prickles along stem, short ocrea at nodes
¬ Fine-stellate hairs along margins and mid-vein of leaves
¬ Small reddish, pinkish, or whitish flowers with nearly persistent perianth parts
Plant Height: Usually 0.9 – 1.8 m in length (2,6), reaching a height of 1.5 m (7).
Subspecies/varieties recognized: All varieties and synonyms have been subsumed under P. arifolia (3,4).
Most Likely Confused with: May be confused with Persicaria sagittata(1,6), Fallopia cilinodis, F. convolvulus, and F. scandens, Ipomoea pandurata, I. purpurea, Convolvulus arvensis, Calystegia hederacea, and C. sepium, as well as members of the Araceae family.
Habitat Preference: Found in wet soils, typically in shaded wetlands such as swamps, marshes, wet meadows, and wet ravines, as well as along rivers (1,2,3,6,8,9,10). In coastal states, also found in tidal marshes and near brackish habitats (1,9,24).
Geographic Distribution in Michigan: P. arifolia is found in 15 counties in the southern half of the Lower Peninsula, reaching as far north as Newaygo and Mecosta Counties (5,11,12).
Known Elevational Distribution: In Canada and the U.S.A., P. arifolia has been recorded up to 600 m elevation (3).
Complete Geographic Distribution: Native to the eastern U.S.A. and Canada, extending south into Georgia and Louisiana (3,5,24). P. arifolia is also found in the state of Washington (3,5), a clearly disjunct distribution.
Vegetative Plant Description: The stem of P. arifolia is ridged and covered with reversed prickles as much as 3.5mm in length (2,3,6,8,10,13). Leaves are alternate and simple with entire margins and pinnate venation (6,8,10,24). The brownish, papery ocrea ranges from 8-15mm in length (3,24). Petioles range from 1-13cm long, while leaves range from 4-15cm long and up to 15cm wide (1,2,3,6,9,10,24). Leaves are arrowhead-shaped, hastate with acuminate apices, and have stellate-pubescence on their undersides (1,2,3,5,6,8,9,10,24). From personal observation of herbarium specimens, prickles often continue on the petiole and along the primary vein of the leaf.
Climbing Mechanism: P. arifolia is a scrambler, climbing by use of the prickles and hairs along its stems and leaves, sometimes managing to entangle with other plants or structures (6,10).
Flower Description: The inflorescence of P. arifolia is a capitate raceme with 2-4 perfect flowers per fascicle and a stellate pubescent peduncle with red/pink glands, 1-8cm long (1,3,8,9). The ocreolae that subtend the inflorescence often overlap and may bear marginal cilia and bristles. The peduncle may be armed with retrorse prickles. The pedicels are 0.2-0.3cm long. The perianth can be a mixture of red, pink, or white and is made of 4-5 connate tepals each 5-6mm long (1,3,8,9,10,24). Each flower has 6 (sometimes 8) stamens with pink anthers (1,3,10) and 2 styles (2,3). The ovary is superior (8).
Flowering Time: In North America, P. arifolia begins flowering as early as June (10), however more commonly it flowers in late July-early August and continues into September or October, until the first frost (1,2,3,8,9,13).
Pollinator: Studies of pollen shape suggest that species of Persicaria are insect pollinated (13).
Fruit Type and Description: The fruit of P. arifolia is a dark-brown to black glabrous achene (1,2,3,8,9). It is lenticular/biconvex, approximately 3.5-6mm long and 3 mm thick (1,2,3,9). Personal observation suggests that the perianth is persistent and covers most of the fruit.
Seed Description: Fruits of P. arifolia contain one seed, but the fruit does not open (14,15).
Dispersal Syndrome: The fruits are mostly destroyed by digestion, however it is possible that germination could occur if the seed were vomited by a bird, or dispersed by destruction of a bird carcass before digestion and after death (16). The fruit is most probably gravity dispersed.
Distinguished by: The leaf of Persicaria arifolia might be confused with that of P. sagittata, however P. arifolia has wider leaves, more hastate bases, and longer petioles (1,2,3). P. arifolia is likely confused with Fallopia cilinodis, F. convolvulus, and F. scandens, which have deeply cordate leaves. Again, P. arifolia can be distinguished by the hastate leaf bases (1,2,3).
Ipomoea pandurata, I. purpurea Convolvulus arvensis, Calystegia hederacea, and C. sepium, have larger, funnelform flowers distinguishing them from the tiny, more urceolate shaped flowers of P. arifolia (1,2,3). In addition, all these members of the Convolvulaceae are unarmed stem twiners, while Persicaria arifolia climbs by means of prickles (6,10).
Leaf shapes in P. arifolia and members of the genus Arum (Araceae) are similar, however the spathe and spadix inflorescence of the Araceae and non-climbing/non-twining habit distinguishes them from P. arifolia (1,3).
Other members of the family in Michigan (number species): Rheum (1), Rumex (13), Polygonella (1), Fallopia (5), Persicaria (14), Polygonum (6), Fagopyrum (1), Bistorta (1) (11,12).
Ethnobotanical Uses: Some members of the genus (especially Persicaria sagittata) produce photodynamic chemicals that can produce photosensitivity effects when in contact with animal skin; however specific uses of P. arifolia appear to be unstudied (17).
Phylogenetic Information: Polygonaceae is included in the Polygonales in the Caryophyllid clade of Eudicots (18). Polygonaceae includes 35 genera and 442 species and is divided into 2 subfamilies: Eriogonoideae & Polygonoideae, consisting of 19 and 16 genera, respectively (18). Within Polygonoideae, Persicaria is divided into the sections Tovara, Echinocaulon, Cephalophilon, Persicaria, and Rubrivena (3,12,19,20). P. arifolia is placed in the section Echinocaulon (3,12,19,20).
Interesting Quotation or Other Interesting Factoid not inserted above: The first component of the common name for Persicaria arifolia, “Halberd-leaf”, references a medieval weapon which combined both a battle-ax and pike on the same handle (23), while “tearthumb” is most likely a reference to the prickles growing along its stem. It is endangered in Illinois and threatened in Tennessee and considered a wetland weed in most states (5). The small fruits are an important food source for waterfowl (24,25).
Literature and websites used:
- Fernald, M. L. 1950. Gray’s Manual of Botany, 8th ed. New York, USA: American Book Company.
- Gleason, H.A. 1963. The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada. New York, New York, USA: Hafner Publishing Co., Inc.
- Hinds, H.R. & C.C. Freeman 2005. Flora of North America, Vol. 5: 32. Persicaria. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250060695
- Tropicos.org. Missouri Botanical Garden. http://www.tropicos.org/Name/26000831. 24 January 2011
- USDA, NRCS. 2008. The PLANTS Database (http://plants.usda.gov/ 24 January 2011). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
- Robert W. Freckmann Herbarium, University of Wisconsin-Stevens Point. Wisconsin Plants Website (http://wisplants.uwsp.edu). 2 February 2011.
- C.V. Starr Virtual Herbarium. The New York Botanical Garden. http://sweetgum.nybg.org/vh/specimen.php?action=view+checked&irn=1278519&irn=1272420. 2 February 2011.
- Illinois Plant Information Network (ILPIN) http://nrs.fs.fed.us/data/il/ilpin/.
- Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the Vascular Flora of the Carolinas. Chapel Hill, North Carolina, USA: The University of North Carolina Press.
- Parkhurst, H.E. 1903. Trees, shrubs and vines of the northeastern United States. New York, New York, USA: C. Scribner’s Sons
- Voss, E.G. 1985. Michigan Flora Part II: Dicots. Ann Arbor, Michigan, USA: Cranbrook Institute of Science.
- Michigan Flora Online. A.A. Reznicek, E.G. Voss, & B.S. Walters. February 2011. University of Michigan Web. 4 February 2011. http://michiganflora.net/information.aspx.
- Wodehouse, R.P. 1931. Pollen grains in the identification and classification of plants VI. Polygonaceae. American Journal of Botany 18(9): 749-764.
- Seymour E.L.D. 1946. “The New Gardening Encyclopedia”. New York, New York, USA: American Book-Stratford Press, Inc.
- Young, J.A. and C.G. Young. 1992. Seeds of Woody Plants in North America. Portland, Oregon, USA: Dioscorides Press.
- Ridley, H.N. 1930. The Dispersal of Plants Throughout The World. Ashford, Kent, USA: L. Reeve & Co., LTD.
- Plants For A Future, 1996-2010. Last modified: June 2004. http://www.pfaf.org/user/Plant.aspx?LatinName=Polygonum%20sagittatum.
- Judd, W.S., C.S. Campbell, E.A. Kellogg, P.F. Stevens, and M.J. Donoghue. 2002. Plant Systematics: A Phylogenetic Approach, Second Edition. Sunderland, Massachusetts, USA: Sinauer Associates, Inc.
- Kim S.-T. and M.J. Donoghue. 2008. Molecular phylogeny of Persicaria (Persicarieae, Polygonaceae). Systematic Botany 33(1): 77-86.
- Park, C.-W. 1986. Nomenclatural typifications in Polygonum section Echinocaulon (Polygonacease). Brittonia 38(4): 3944-406.
- Stearn W.T. 1992. Stearn’s Dictionary of Plant Names for Gardeners. London, UK: Cassell Publishers Limited.
- Brown, R.W. 1956. Composition of Scientific Words. Washington, D.C., USA: Smithsonian Institution Press.
- Merriam-Webster. An Encyclopædia Britannica Company. http://www.merriam-webster.com/dictionary/halberd. 7 March 2011.
- Silberhorn, G. 1992. Technical Report Wetland Flora, Halberd-leaved Tearthumb, Hastate-leaved Tearthumb, Polygonum arifolium L. Center for Coastal Resources Mgmt: 92-93.
Image Credits (all used with permission):
1. Image of leaf from kgNaturePhotography.com
2. Image of flower from David G. Smith, downloaded from http://www.delawarewildflowers.org/plant.php?id=1523
3. Species distribution map, derived from the Michigan Flora Online.
Primary Author: Andrew Quebbeman with editing by John Bradtke, Robyn J. Burnham, and Cristine V. Santanna
© Robyn J. Burnham
For additional information on Michigan Plant Diversity web pages please contact Robyn J. Burnham via email: rburnham“at”umich.edu