Rudbeckia hirta Linnaeus

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.

july_20_04.gthmb can't be loaded. Rudbeckia hirta is a species of prolific annual biennial or perennial plants that grow to 1 m in height. They are taprooted or have fibrous roots. 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:

The species belongs to the Asteraceae family.


The genus 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.

Common names

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.


july_09_10.gthmb can't be loaded. Rudbeckia hirta var. pulcherrima Farw. has also been known as:


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 throughout.


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Flower heads


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. map_na.jpg can't be loaded.


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.

The month, day and picture number might be followed by a letter:

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.


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aug_27_03s.mthmb cannot be loaded. 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 mildew.

Flower heads

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Fruits, seeds, receptacle, phyllaries

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