Genus of the Week
Week of August 31 - September 6
This page has been created for people who want to learn more about plants, especially in the
context of their taxonomy (Latin names, etc.). This is by no means an exhaustive list of
all available Web resources for a particular genus.
If you like this page, you should also visit the Land of the Glandular Trichomes
, a microscopic look at plants in the Lamiaceae family.
This week's genera:
Aureolaria and Agalinis (formerly known as Gerardia)
Subclass: Dicotyledoneae
Superorder: Asteridae
Order: Scrophulariales
Family: Scrophulariaceae - The Snapdragon or Figwort Family
Number of Species: At least 11
Root: Aureolaria is from the Latin "aureus", meaning golden yellow. According to
the Northern Prairie Science Center, Agalinus means
"remarkable flax" in Latin. Gerardia was named after the herbalist, John Gerarde, who
died in the early 1600's. Some species have been labeled as both Aureolaria or
Agalinis, depending on the source.
The recently divided genus Gerardia contained a number of species with the beautiful
fused-corolla flowers typical of the Scrophs. The genus Aureolaria is not recommended for
creating dried flower arrangements, since individuals normally turn black after being picked and
dried. Plants in this genus are also known to be semi-parasitic on oak trees. They do this by
means of haustoria, specialized structures borne from their roots that actually penetrate through
the vascular bundles of the roots of the host tree. Another Genus of the Week that is semi-parasitic is
Comandra (Bastard Toadflax).
Here are a few links to images and descriptions of different Aureolaria and Agalinis species:
- Make the Parasitic Plant Connection by viewing a photo of the
haustorium of Aureolaria flava (Smooth False Foxglove). You can also see a .jpeg of
this species
in flower. Brought to you by the Department of Plant Biology at the University of Southern
Illinois.
- Agalinis
aspera (Rough Gerardia) and
A. tenuifolia (Slender Gerardia) are some of the native plants of the North Dakota
Grasslands. Stop by the Northern Prairie Science Center for photos and descriptions.
- A. navasotensis is a newly
described species that apparently is found only in Moore's Hill Outcrop in Grimes County, Texas.
- Be sure to make another stop at the Parasitic Plant Connection to see the steps involving
initiation of haustorium in A. purpurea (Purple Gerardia). Scroll down to where it
says "Haustorial Initiation in Agalinis".
References:
- Heywood, V.H., ed. Flowering Plants of the World. New York, Oxford University Press: 1993.
- Neiring, William A. and Nancy C. Olmstead., eds. The Audubon Society Field Guide to North American Wildflowers, Eastern Region. Alfred A. Knopf, New York: 1979.
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