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Plant of the Week: Helianthus maximiliani Maximilian Sunflower

Helianthus maximiliani Maximilian Sunflower — Perennial sunflowers such as the Maximilian Sunflower are long lived in the garden but require a lot of room. (Image courtesy Gerald Klingaman.)


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Though I’m a professed plant nerd, I also have other interests.  It always intrigues me when several of my interests are brought together by a plant.  Maximilian Sunflower (Helianthus maximiliani) is a good example, bringing together plants with exploration, American history and art. 

Maximilian sunflower is a large perennial in the sunflower family that was originally native to the tall grass prairie region from Texas to Ohio and into the prairie region of southern Canada.  It grows from a dense semi-woody rhizomatous root stock and produces annual stems that grow 4-10 feet tall with the clump, in a good location, spreading to 6 feet or more across.

Leaves are willow shaped, coarse textured and hairy with wavy margins, and as long as 10 inches at the base, half that at the top.  The leaves have a single vein running the length of the leave and are often covered with a gray-white pubescence. Flowers appear in late summer and early fall at the top of the plant in terminal, spike-like clusters.  Individual blooms are to three inches across with a green to brown center with about 15 ray flowers.  Blooms are produced over about a six week period.

Maximilian sunflower is named after Prince Alexander Philipp Maximilian zu Wied-Neuwied of Germany (1782-1867) who traveled in the Great Plains between 1832 and 1834.  He was a first class naturalist interested in plants, animals and minerals and collected many specimens as he traveled by steamboat up the Missouri River to the Yellowstone River.  He was accompanied on the expedition by Karl Bodmer (1809 – 1893), a Swiss born artist credited with producing some of the most accurate watercolors of individual native chiefs and scenes from the Missouri River Valley. 

Maximilian and Bodmer had ample time to explore the countryside surrounding the river for their steamship was often aground or hung up in snags along the river course.  In his 1840 telling of his journey he often laments the loss of his specimens – especially rock samples – because crew members were forever tossing them overboard to lighten the load.   Because the route he traveled had been traversed for over 20 years – including collections by prior naturalists – he managed to find only one new plant.  The sunflower bearing his named was named in 1836 by Heinrich Adolf Schrader from material Maximilian collected. 

This big, robust sunflower is a delight in the large landscape but not suited to the small perennial border.  It needs room to spread, and according to one reference, is allelopathic which means it produces compounds in its roots that inhibit the growth of other plants around it.  It makes a bold statement in large background beds or at the edge of the woodland.  Plants grow best in a clay-loam soil that is kept watered during dry periods.  But once established Maximilian sunflower will tolerate any Arkansas drought.  Plants are hardy from zones 3 through 9. 

For more information about horticulture or to see other Plant of the Week columns, visit Extension's Web site, www.uaex.edu, or contact your county extension agent. The Cooperative Extension Service is part of the U of A Division of Agriculture.

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