Helianthus maximilianii (Maximilian Sunflower)

Plant Info
Also known as:
Genus:Helianthus
Family:Asteraceae (Aster)
Life cycle:perennial
Origin:native
Habitat:sun; sandy soil,
Bloom season:July - October
Plant height:2 to 10 feet
Wetland Indicator Status:GP: FACU MW: UPL NCNE: UPL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 7+petals

[photo of flowers] Flowers are at the top of the plant and at the end of stems that arise from leaf axils in the upper half of the plant. Individual flowers are 2 to 4 inches across with 15 to 30 yellow ray flowers (petals) and yellow disk flowers.

[photo of bracts] There are a few layers of bracts behind the flower; bracts are long, narrow and spreading, and covered in short, appressed hairs. Flower stalks are ½ to 4 inches long, often creating what looks like a long column of flowers at the top of the plant.

Leaves and stem: Leaf attachment: alternate Leaf attachment: opposite Leaf type: simple

[photo of leaves] Leaves are up to 10 inches long and 2 inches wide, grayish green, folded up along the center vein and arching, with a pointed tip, tapering at the base and a short or no stalk. Leaves are mostly toothless but sometimes have small teeth; the texture is rough on both upper and lower surfaces. Attachment is mostly alternate but is opposite in the lower part of the plant. The stem is roughly hairy, especially near the top, and is green or purplish.

Fruit: Fruit type: seed without plume

The center disk forms a head of dry seed, each about 1/8 inch long and without a tuft of hairs, but with 2 bristly scales.

Notes:

Maximilian Sunflower most closely resembles Sawtooth Sunflower (Helianthus grosseserratus), but the latter has coarsely toothed leaves with longer stalks, and a hairless stem that often has a white bloom, where Maximilian Sunflower leaves are mostly toothless and its stem rough from short hairs.

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More photos

Photos by K. Chayka taken at Fort Snelling State Park, Hennepin County. Other photos courtesy Peter M. Dziuk

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Pat - Meeker co.
on: 2012-02-15 16:02:06

There are some growing in a field south of Darwin. I grew these in my native wildflower garden. They get very tall and want to flop over . Cutting them back to ground level on first of August results in a nice short flowering clump, just like a Buffalo would do.

Posted by: Rosie
on: 2013-07-22 12:28:08

What is the biological function of the tiny hairs covering the bracts? Does it have something to do with insects? Thank you.

Posted by: K. Chayka
on: 2013-07-24 07:03:41

Rosie, that's a good question. For some species, and particularly for hairy leaves, it sometimes has to do with moisture retention but we don't know about hairy bracts or this species in particular. We'd love to have somebody research that kind of thing for us.

Posted by: Brian - Le Sueur County
on: 2016-09-24 23:32:41

There are some magnificent stands of Maximilian Sunflower growing along Cannon River Road in Le Sueur County in the vicinity of Murphy Wildlife Management area. I visited today, and they're pretty much at their peak, forming an undulating yellow sea (it was a bit windy...).

Posted by: Jo S - SW corner near Rowena
on: 2017-03-16 01:44:38

See them in idle fields. I tried to grow in back of flower beds but gave up. They are huge plants well over my height. They get pretty woody and are pretty tough but still managed to flop over taking nearly 5 feet diameter! In my garden I found they bloomed extremely late (often not starting before killing frost). Only luck I had was in shelter corner of wood fence (windbreaker)which supported it and let it not flop and extended the season due to microclimate protection (corner faced SW). Only 1 good year out of 7 but it was very impressive with thousands of flowers. It takes determination to uproot this plant unless you own dynamite. Similar to lythrum. Roots woody, thick and go to hell and back again.

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