Prenanthes altissima Linnaeus
The words or terms in red
(actually dark orange) in the text are defined in a
Prenanthes altissima are perennial
plants with erect stems that are from 40 cm to more than 2 m high, hence the
epithet of the name.
They grow from thickened, knotty,
The plants are usually unbranched, except toward the
apex where the
flower heads occur.
The species is
native to North America.
The chromosome number of the plant
(2n) is 16.
The plant belongs to the
In Greek, πρηνησ
(prênês) means nodding and
means flower, the genus name alluding to the drooping flower heads.
In Latin, altus means high, and altissimus is its
superlative; the epithet refers then to the
large height of Prenanthes altissima that can reach over 2 meters.
Some of the vernacular names of
Prenanthes altissima are
Tall Rattlesnakeroot, Rattlesnake Root, Tall White Lettuce and
Lion's Foot. The French vernacular name is Prenanthe élevée.
has also been known as:
- Chondrilla altissima (L.) Lam.
- Harpalyce altissima (L.) D. Don ex Beck
- Harpalyce cordata (Willd.) D. Don ex Beck
- Nabalus altissimus (L.) Hook. var. cordatus (Willd.)
Torr. & A. Gray
- Nabalus altissimus (L.) Hook. var. deltoideus
(Elliott) Torr. & A. Gray
- Nabalus altissimus (L.) Hook. var. dissectus
Torr. & A. Gray
- Nabalus altissimus (L.) Hook. var. ovatus Torr. & A. Gray
- Nabalus altissimus (Linnaeus) Hooker
- Nabalus cordatus (Willd.) Hook.
- Nabalus deltoideus (Elliott) DC.
- Prenanthes altissima L. forma hispidula (Fernald) Fernald
- Prenanthes altissima L. var. cinnamomea Fernald
- Prenanthes altissima L. var. deltoidea (Elliott) Farw.
- Prenanthes altissima L. var. hispidula
Fernald in Brainerd, Jones, & Eggl.
- Prenanthes altissima L. var. ovata (Torr. & A. Gray) Farw.
- Prenanthes altissima var. cinnamomea Fernald
- Prenanthes altissima var. hispidula Fernald
- Prenanthes cordata Willd.
- Prenanthes deltoidea Elliott
Prenanthes altissima is recognized by:
The other Prenanthes species found in Québec have a larger number of
florets and phyllaries. As a general rule, leaf shape is unreliable as a guide
to identification because it is highly variable within each species of
- its numerous bell-shaped drooping greenish-yellow flower heads
- its narrow involucres with 5 pale green
- its 5 ray florets
- its pale yellow to greenish yellow
- Greenish to purplish.
- With winged petioles.
- Quite variable in shape, with usually
or triangular blades.
- With entire or shallowly
often deeply into 3 lobes
(or less often 5)
- Between 4 to 15 cm wide by 2 to 16 cm long.
- Gradually smaller as they ascend the central stem.
- Containing a white latex.
Halictid bees, beetles, and other insects may feed on the
but they are not effective pollinators.
- In narrow or spreading paniculiform
arrays terminating the stem.
- With a cylindric involucre,
about 1 cm long and 2.5 mm wide.
- About 3/4 inch long and 1/2 inch across.
- With 4 to 6, but usually 5 pale green
- With 4 to 6, but usually 5 pale yellow to greenish yellow
- Without disk florets.
- Blooming from late summer into the fall and lasting about a month
in my area, 25 km north of Montréal.
- Pollinated by bumblebees that
suck the nectar.
- A brown to tan cypsela.
- with a usually whitish or pale yellow and at times reddish brown
pappus, about 6 mm long.
Habitats of Prenanthes altissima include rich mesic woodlands,
rocky upland woodlands, sandy woodlands, bluffs and shaded ravines,
woodland borders, swamps and seeps, and shaded to partially shaded riverbanks.
The species is found in deciduous woodlands where
Sugar Maple (Acer saccharum), American Basswood (Tilia americana),
and American Beech (Fagus grandifolia) are often present as canopy trees.
Prenanthes altissima is found in the eastern half of Canada and the USA.
The map shows the Canadian provinces and USA states where the plant
can be found.
Even though it has a bitter taste, White-Tailed Deer occasionally browse
on the foliage of Prenanthes altissima.
The Iroquois used a poultice against
dog and rattlesnake bites, hence one of the common name Rattlesnake root.
The photos of the gallery were taken either with one of the following:
Minolta DiMAGE 7,
Canon PowerShot A530,
Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective,
Fujifilm A 610 and
EPSON Perfection 1650 (scanner).
The title in the window shows the date when the picture was taken,
i.e. jan_30_06... would mean that the photo was taken on the 30th of
January, the 06 is for the 6th picture taken that day.
The month, day and picture number might be followed by a letter which I use
to identify the system used to take the picture.
Click on the thumbnails to get larger view.
The original photos are usually in TIFF format,
the photos shown are generally in JPEG format,
often of dimensions one half (surface one quarter)
for loading time reduction.
The leaves were scanned at 300 dpi,
and the dimensions of the resulting picture divided by 2 (area divided by 4);
this allows to measure the dimensions of the leaves.