Download Joe-pye weed - Draft

Joe-Pye Weed (Eupatorium maculatum subsp. bruneri)
Global: G5T4T5Q Provincial: S1 COSEWIC: n/a BC List: Red
Historical South Coast Occurrence Range
Distribution: Widespread in North America, Joe-Pye weed occurs throughout much of the
United States, and in Canada from southern British Columbia east to Ontario. It is globally
secure but extremely rare in southwestern BC. This species has been found at several sites
along the lower Fraser River, but only one site, Kirkland Island at Steveston, has recently
been confirmed. The populations previously known from Huntingdon, Delta, Point Grey,
Sea Island and Shady Island all appear to be extirpated (B.C. Conservation Data Centre
2008a). Joe-Pye weed has also been reported in a bog near Revelstoke (Bjork, personal
communication 2007), but that population has yet to be confirmed.
Description: A member of the Aster Family (Asteraceae), this showy evergreen perennial
reaches up to 2 meters in height. Maculatum means “spotted” and refers to the stems which
are often purple-spotted or completely purple. Stems bear narrow, pointed saw-toothed
leaves, up to 20 cm long. The leaves occur in whorls of 3 or 4. Both the stems and lower
surfaces of the leaves are covered in short curly hairs. The fluffy lavender-coloured
inflorescence at the top of the stem is a rounded mass of hundreds of tiny flower heads.
Each flower head is just over 1 cm long and surrounded at its base by 2 or 3 rows of tiny
scale-like bracts. The flower head encloses up to 22 tiny disk flowers. When the flower head
opens, hair-like stigmas from the disk flowers can be seen protruding from the top of the
head. After pollination, each disk flower produces a fruit (“achene”) that is 3-5 mm long and
contains a single seed. Achenes are adapted for wind dispersal with a tuft of hair-like bristles
that drifts like a miniature parachute in the wind. Plants bloom from July to early September.
Note on Taxonomy: Joe-Pye weed is a subspecies of Eupatorium maculatum. The
taxonomy of this species has been revised numerous times and as a result, Joe-Pye weed is
known under several different botanical names. The Illustrated Flora of British Columbia,
the B.C. Conservation Data Centre and E-Flora BC list this subspecies under Eupatorium
maculatum subsp. bruneri (Douglas et al. 1998; Klinkenberg 2006). However, more recent
publications, including the Flora of North America, list it under Eutrochium maculatum var.
bruneri (Lamont 2006; Lamont 2004). To add to the confusion, it was also previously
known as Eupatoriadelphus maculatus var. bruneri and Eupatorium bruneri (Lamont 2006;
Schmidt and Schilling 2000). For the sake of consistency, we will follow the Illustrated
Flora of British Columbia (Douglas et al. 1998) for this guide and refer to this subspecies as
Eupatorium maculatum subsp. bruneri.
Look’s Like?
Joe-Pye weed may be confused with its close relative Eupatorium maculatum subsp.
maculatum, a popular garden plant and possible escapee in the Lower Mainland. So far, all
populations of Joe-Pye weed found in the Lower Mainland are confirmed to be Eupatorium
maculatum subsp. bruneri. The two subspecies look nearly identical but can be distinguished
by the location of hairs on the plants. E. maculatum subsp. bruneri has dense curly hairs on
the stems and undersides of the leaves, while E. maculatum subsp. maculatum generally has
hairs only within the inflorescence.
Habitat: Joe-Pye weed grows in full sun to dappled shade in wet to moist habitats at low
elevations. You will find this species in swamps, bogs, at the edges of cranberry fields and
slow moving streams, at pond margins and in moist forest openings. In BC Joe-Pye weed
occurs in tidal marshlands, gravel river channels and bogs. This species thrives in calcareous
soils.
Critical Features
 The ability of Joe-Pye weed to recover in BC is limited by the fact that this species
appears to produce few seedlings, despite the abundance of flowers and seeds produced
(B.C. Conservation Data Centre 2008a).
 As a wetland species, Joe-Pye weed is vulnerable to changes in site hydrology and water
chemistry.
Seasonal Life Cycle
Jan Feb Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Flowering
Achene
production and
dispersal
Threats
 Because Joe-Pye weed is known only from a few sites in BC and occurs within the
Lower Mainland on unprotected lands, it is highly threatened by development,
recreational pressures and associated habitat loss. In BC this species is rapidly
declining, with more than two thirds of the populations lost over the past century.
 The population at Kirkland Island is vulnerable to being out-competed by aggressive
invasive wetland species, especially purple loosestrife (Lythrum salicaria), reed
canarygrass (Phalaris arundinacea) and tall fescue (Festuca arundinacea).
Conservation Objectives
 The only known populations of Joe-Pye weed in the province are on unprotected lands.
Protection of these sites is urgently needed to prevent the extirpation of this species in
BC.
 A targeted inventory is also needed to determine if undiscovered populations exist
elsewhere within our region.
 Research into the specific ecological requirements and population dynamics of this
species would be helpful in developing a recovery strategy for this species.
Management Practices Check List
 Maintain suitable habitat within the historical range of this species. Avoid draining
ponds and lakes, infilling wetlands and other activities that drastically alter water levels
and suitable habitat.
 Where suitable habitat occurs along creeks, ponds and lakes, ensure activities that occur
upstream and along the shoreline do not alter water chemistry or introduce toxic
chemicals.
 Avoid activities that can result in trampling of plants. This is especially important in
shoreline areas where there are recreational trails.
 Protect the seed bank by avoiding soil compaction, digging or dredging.
 Prevent the introduction and spread of invasive wetland plants, especially aggressive
competitors like purple loosestrife, which can be difficult to control once they are
established. When controlling invasive plants, take precautions to minimize disturbance
to Joe-Pye weed populations, especially the seed bank.
 Prevent plant harvesting and picking of flowers. This species looks nearly identical to
the more common Joe-Pye weed grown in gardens and it is also used for medicinal
purposes.
Main References/Literature Cited
B.C. Conservation Data Centre. 2008a. Conservation Status Report: Eupatorium maculatum
ssp. bruneri. [http://a100.gov.bc.ca/pub/eswp/]. B.C. Ministry of Environment, Victoria,
B.C. Accessed March, 2008.
B.C. Conservation Data Centre. 2008b. BC Species and Ecosystems Explorer
[http://a100.gov.bc.ca/pub/eswp/]. B.C. Ministry of Environment, Victoria, B.C.
Accessed June, 2008.
Bjork, Curtis. 2007. Personal communication.
Douglas, G.W., D.V. Meidinger, and J. Pojar (editors). 1998. Illustrated Flora of British
Columbia. Volume 1: Gymnosperms and Dicotyledons (Aceraceae Through
Asteraceae). B.C. Ministry of Environment, Lands & Parks and B.C. Ministry of
Forests. Victoria. 436 p.
Klinkenberg, Brian. (Editor) 2006. E-Flora BC: Electronic Atlas of the Plants of British
Columbia [www.eflora.bc.ca]. Lab for Advanced Spatial Analysis, Department of
Geography, University of British Columbia, Vancouver. Accessed June 2008.
Lamont, Eric E. 2006. 393. Eutrochium Rafinesque. In: Flora of North America North of
Mexico, Vol. 21 (Magnoliophyta: Asteridae, part 8: Asteraceae, part 3): 461-462, 474475.
Lamont, Eric E. 2004. New combinations in Eutrochium, an earlier name for
Eupatoriadelphus. Sida 21: 901-902.
NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life
[http://www.natureserve.org/explorer/]. Version 7.0. NatureServe, Arlington, Virginia.
Accessed June, 2008.
Schmidt, G.J. and E.E. Schilling. 2000. Phylogeny and Biogeography of Eupatorium
(Asteraceae: Eupatorieae) Based on Nuclear ITS Sequence Data. American Journal of
Botany 87(5): 716-726.
Image credits:
Cluster of plants and close-up of two flowering stems by Ben Legler.
Close-up of flower heads by Cal Lemke.
Illustration of disk flower by Cindy Sayre.
Habitat photograph by Brian Klinkenberg.