Rudbeckia hirta Linnaeus
The words or terms in red
(actually dark orange) in the text are defined in a
Rudbeckia hirta is a species of
perennial plants that grow to 1 m in height.
They are taprooted or have
The seeds do not have a pappus.
The species has 38 chromosomes.
They are native to North America and
botanists recognize 4 varieties
of the species:
- Rudbeckia hirta var. angustifolia that is found in the
southeastern USA from South Carolina and Georgia to Texas
- Rudbeckia hirta var. floridana, that, as the
is endemic in Florida
- Rudbeckia hirta var. hirta that is found in the eastern
USA, mostly in the Appalachian Highlands
- Rudbeckia hirta var. pulcherrima that is found all over
the US States but for Nevada and Arizona (it has in fact
naturalized from Washington to
California); it is also found in all the Canadian provinces.
The species belongs to the
was named for Olaus Rudbeck (1630-1702), the Swedish botanist
and physician and is son Olaus Olai Rudbeck (1660-1740)
professors at Uppsala University, predecessors of Linnaeus.
Olaus Rudbeck (also known as Olof Rudbeck the Elder, to distinguish him from
his son, and occasionally with the surname Latinized as Olaus Rudbeckius)
was a scientist and writer, professor of medicine at Uppsala University and for
several periods rector magnificus of the same university.
Rudbeck was one of two early discoverers of the lymphatic system in 1651;
in Uppsala he had an extensive activity,
including the foundations of the botanical garden,
Alfred Nobel was a descendant of Rudbeck through his daughter Wendela,
who married one of her father's former students, Peter Olai Nobelius.
In Latin hirtus means hairy and that is the case of the stems,
leaves and phyllaries of the species, so that
the epithet is appropriate.
The vernacular name of
Rudbeckia hirta is Black Eyed Susan that is also written
Black-eyed Susan or Blackeyed Susan.
Some of the French vernacular names are Rudbeckie hérissée,
Rudbeckie dressée, Marguerite jaune and Becky Varié.
Rudbeckia hirta var. pulcherrima Farw. has also been known as:
- Rudbeckia bicolor Nutt.
- Rudbeckia hirta L. var. corymbifera Fern.
- Rudbeckia hirta L. var. lanceolata (Bisch.) Core
- Rudbeckia hirta L. var. sericea (T. V. Moore) Fern.
- Rudbeckia hirta L. var. serotina (Nutt.) Core
- Rudbeckia longipes T. V. Moore
- Rudbeckia sericea T. V. Moore
- Rudbeckia serotina Nutt.
- Rudbeckia serotina Nutt. var. corymbifera (Fern.)
Fern. & Schub.
- Rudbeckia serotina Nutt. var. lanceolata (Bisch.)
Fern. & Schub.
- Rudbeckia serotina Nutt. var. sericea (T. V. Moore)
Fern. & Schub.
With its abundance, its large size, its bright orange flowers and dark center
(hence the Black-eyed Susan common name), once usually come
across Rudbeckia hirta in Québec and much less often across the other
three species of Rudbeckia.
However the four species of Rudbeckia being somewhat similar,
the following key allows to start differentiating them, and a closer
inspection should readily confirm or infirm the identification.
1. If the leaves are bluish green,
glaucous and the ray florets are bright
yellow it is Rudbeckia laciniata var. laciniata. For the other
three species, the leaves green, not glaucous; ray florets yellow-orange.
2. If the plant is stoloniferous
with rosettes forming at
stolon apices the
species is Rudbeckia fulgida var. speciosa.
3. If the leaves are three lobed
the species is obviously Rudbeckia triloba var. triloba.
4. And if the plant does not have the above characters the species is then
Rudbeckia hirta var. pulcherrima.
This last species is in fact the most widespread and most common in Québec;
that is, if in Québec you come across a Rudbeckia, it is likely to be
Rudbeckia hirta var. pulcherrima.
The stems are branched mostly beyond mid heights and more or less leafy
- Basal leaves
- Cauline leaves blades
or broadly linear.
- Cauline leaves alternate.
- Margins entire or
- Faces scabrous to
- Heads borne singly or in
- Phyllaries hairy, measuring up to
- Receptacles hemispheric to
- With 8 to 16 ray florets
uniformly yellow to yellow-orange or, at times, with a
basal maroon or red splotch, 15 to 45 mm long by 5 to 10 mm wide.
- With 250 to 500 disk florets,
forming a brown disk from 12 to 22 cm in diameter.
- In bloom form the end of June to the end of September, and, at times,
till the end of October in my area, 35 km north of Montréal.
Rudbeckia hirta var. angustifolia is found in moist meadows but
drained and forest edges but it is drought tolerant and grows best in full sun.
While native to North America
Rudbeckia hirta var. angustifolia
is frequently observed throughout the world as a naturalized plant.
The map shows the distribution for North America where the species is native.
Numerous cultivars Rudbeckia hirta
have been selected for garden planting; some popular ones
include Double Gold, Indian Summer, and Marmalade.
The roots of Rudbeckia hirta have been used in a warm infusion
to wash on sores and snake bites, and to make medicinal drinks for treating
colds and worms in children.
Ooze from the roots had been used as drops for earaches.
Rudbeckia hirta is the state flower of Maryland.
Though not native to the state of Maryland, it grows throughout the state
and presents beautiful waves of orange or yellow in fields from late summer to
autumn. It was adopted as the floral emblem of the state on April 18, 1918, by
an act of the Maryland General Assembly, it's color blending nicely with the
Maryland State Flag, the state bird, the state insect and the state cat.
The photos of the gallery were taken either with one of the following:
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.
- Minolta DiMAGE 7.
- Canon PowerShot A530
- Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective.
- EPSON Perfection 1650 (scanner).
The month, day and picture number might be followed by a letter:
- c for the Canon Xt Rebel.
- a for the Canon A530.
- m for the Minolta DiMAGE 7.
- s for the EPSON scanner.
Click on the thumbnails to get larger view.
The original photos are usually in TIFF format,
the photos shown are generally in JPEG format,
usually of dimension one half (surface one quarter)
for loading time reduction.
The lilas flowers on the picture on the right are Lythrum salicaria.
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.
The two leaves on the right show some powdery
Fruits, seeds, receptacle, phyllaries