Lobelia siphilitica (Blue Lobelia)

Plant Info
Also known as: Great Blue Lobelia, Blue Cardinal Flower
Family:Lobeliaceae (Lobelia)
Life cycle:perennial
Habitat:part shade, sun; moist fields, along shores
Bloom season:July - October
Plant height:1 to 4 feet
Wetland Indicator Status:GP: OBL MW: OBL NCNE: FACW
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: irregular Flower shape: tubular Cluster type: raceme Cluster type: spike

[photo of flowers] Elongating spike-like raceme of irregular tubular flowers about 1 inch long on a short flower stalk, with a leafy bract at base of the stalk. Color ranges from light blue to bright blue-violet. Flowers have 3 pointed lobes below and 2 smaller lobes above, sometimes erect but usually curved back. In between the upper lobes is a curved style. The lower center lobe has 2 small bumps near the throat, with a spot of white at the top of the bump, and white stripes on the outside of the throat. The calyx holding the flower has long narrow lobes, sometimes with long hairs around the edges. Leafy bracts become smaller as they ascend the stem. The cluster is typically densely packed at the top and a bit looser towards the bottom, with flowers blooming from the bottom up

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

[photo of leaves] Leaves are 2 to 6 inches long and up to 2 inches wide, irregularly toothed, hairless or sparsely hairy, pointed at the tip, alternately attached with no leaf stalk. Shape is somewhat variable and may be elliptical, lance-like or only slightly narrowed toward the base. The stem is unbranched, ridged, and may have short hairs scattered along the ridges.

Fruit: Fruit type: capsule/pod

[photo of seed] Fruit is a small 2-chambered capsule, each chamber containing many tiny, oval, semi-translucent golden brown seeds. Seeds are densely covered in a network of fine ridges and many shiny scale-like appendages, almost like shingles. The photo doesn't do them justice. :-)


Blue Lobelia makes a great garden plant—butterflies love it. It is doing quite well in my own poorly drained clay soil in full sun, blooming most of the summer through early fall. The Lobelia genus was once in its own Lobeliaceae family, then was moved to the Campanulaceae (Bellflower) family but is now back in Lobeliaceae. There are 2 varieties, both found in Minnesota. Var. siphilitica is an eastern species where Minnesota is on the western edge of the range; it has leaves typically at least ¾ inch wide, 20 or more flowers in the cluster, and is hairy to varying degrees. Var. ludoviciana is a western species where Minnesota is on the eastern edge of the range; its leaves are less than ¾ inch wide, typically has 6 to 20 flowers, and is mostly hairless.

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More photos

Photos by K. Chayka taken at Long Lake and Rice Creek Regional Parks, Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka County.


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

Posted by: Pat - Swift County - 9 miles NE of Benson
on: 2010-08-14 20:40:47

Bought a rocky pasture in 2007 with a small stream cutting through it. Have a big patch of this I noticed today. Blooming, and really nice.

Posted by: Mary Beth - Maplewood, Ramsey County
on: 2010-10-05 22:47:17

Blooming on Oct. 4, 2010 in a wet prairie, almost hidden in tall grasses.

Posted by: Lynnette - Welch, Dakota County
on: 2011-08-14 22:40:22

We live on the bluff overlooking Prairie Island, between Hastings & Red Wing. Our property has sandy, well-drained soil, and yet we have a good stand of blue lobelia growing here in the woods. It finished blooming in August 2011.

Posted by: Rick - Cass Co. Thunder Lake
on: 2011-08-21 16:54:06

Blue Lobelia currently blooming along the lakeshore among Joe-Pye, cattail, and various grasses.

Posted by: Carol - Eden Prairie
on: 2011-09-16 15:25:25

Photographed this flower today on a walk along Purgatory Creek.

Posted by: Gene - Evansville
on: 2013-09-30 16:47:06

I found a couple one foot high single blossomed stems growing a few feet from the lake shoreline in damp soil on a path in heavy clay soil 9/30/2013.

Posted by: Jonathan - Edina, MN
on: 2014-09-16 13:59:19

Several in bloom beside the wetland portion of my prairie planting

Posted by: Linda - Lebanon Hills Park, Eagan
on: 2015-05-29 01:58:57

It was a delight to see this blooming on the shore of O'Brien Lake in Lebanon Hills Park. Only one I've ever seen in the park.

Posted by: Harold - Fairfax in Renville County
on: 2015-09-21 22:53:39

I first found blue lobelia in Grundmeyer Wildlife Management Area west of Gibbon. Later I found some at Fort Ridgely State Park next to a small lake in a prairie area. I went on a tour of Seminary Fen Scientific Natural Area (SNA) near Chaska and they were blooming there too.

Posted by: Kenny h - Rural Mower County
on: 2017-08-17 22:07:58

Found 5 of these treasures in the corner of an old cow pasture...saw them on a drive by...stopped and took photos...lots of other native good stuff there...these were the closest to being blue that I have ever seen.

Posted by: Tom B - Northeast Freeborn County
on: 2017-08-27 11:17:23

I found ramdom plants in half bloom growing in a third year WREP planting. They do not compete very well with canada thistles.

Posted by: Mandy S - Maplewood
on: 2017-09-02 08:16:39

We've found several growing along the shoreline of our ponds. They started blooming in August.

Posted by: Peg S - Found in old pasture in Western WI
on: 2017-09-18 14:14:20

This posture had been treated with Roundup then planted with native prairie species. Lobelia was not one of the forms we planted! but seed bank survived. Beautiful!

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