False Blue Indigo is an introduced (in Minnesota) erect perennial forb, growing from 2 to 4 feet high in bush form on stout smooth green stems. Stems become blackened and woody after seed production but usually remain upright overwinter.
The leaves are trifoliate and alternate, with oblanceolate leaflets that have bluntly pointed tips and smooth margins. There is a pair of small stipules at the base of the leaf stalk. Leaves appear about one month before the flowers. They turn blackish in the fall.
The inflorescence is a spike-like raceme held above the leaves.
The flowers are perfect, 1/2 to 3/4 inch long and are on short stalks with corollas in varying shades of blue. The green calyx is tubular with 5 short rounded lobes which turn outward at the tips when the flower opens. The corolla forms a pea-type flower consisting of 5 petals with the large banner petal turned upward with a notch at the center. There are two lateral petals which enclose keel petals that are usually white, which in turn, house the reproductive parts, which include 10 stamens with yellow anthers and a single style. Large insects such as bumblebees can force open the keel petals where they touch together to reach the pollen contained inside.
Seed: Fertile flowers produce an oblong inflated seed pod with the calyx firmly attached at one end and the remains of the style at the other. The pod is green at first then turning black at maturity. The pod contains a number of brown kidney shaped seeds which are loose in the pod when mature. The pod splits open at maturity to release the seeds by wind or bird dispersion. As the stems and racemes become somewhat woody, pods frequently over-winter. Seeds can be germinated in the spring after cold storage, but not all will be viable.
Habitat: False Blue Indigo forms a shrub like mound, growing from a branched rhizomatous root system. If grown from seed, the plant will require several years of growth before a flower stem is produced and about five years to form a nice clump averaging 3 feet in height. It grows best in rich loamy soil in full sun with moist to mesic conditions. It will tolerate partial shade, and even flower, but the stems will be weak. It is pest free in northern climates where it can survive in zone 3. It can make a good garden specimen but not for cut flower stems, as they turn black when drying begins. Be careful with broadleaf weed herbicides as they will kill the plant.
Names: The true Indigo is Indigofera tinctoria L. hence these Baptisias with blue or white flowers have been termed "false". The genus name Baptisia is from the Greek word bapto, meaning 'to dye' as a dye can be made from the plant but it is inferior. The species name australis means "southern". The author name for the plant classification is complex - see notes below.
Comparisons: Similar in appearance is the False White Indigo, B. alba, which has white flowers, larger leaflets, branched, and is a taller plant with the flower raceme held higher.
Above & Below: Flowers are on short stalks. The blue corolla has five petals, the upper banner petal the largest, with two laterals that wrap around the two keel petals enclosing the reproductive parts. There are 10 stamens and one style.
The trifoliate leaf has a pair of small stipules at the base of the stalk.
Below: 1st photo - The root system forms a taproot with lateral rhizomes. 2nd & 3rd photos - Seed pods formed during the summer are held upright and will have turned blackish by August. Some will split open in the fall, others will hold their seed and remain on the stem throughout the winter. The black mature seed pod has two rows of brown kidney shaped seeds.
Below: 1st photo - The new shoots of spring resemble asparagus until the leaves start to expand on the top of the stems. 2nd photo- Large insects such as this bumblebee are needed to force open the petals to reach the nectar and pollinate the flowers.
Below: 1st photo - The short lobes of the calyx turn outward when the flower opens.
Notes: Eloise Butler's records show that she obtained plants of this species on May 1st 1912 from Kelsey's Nursery in MA and on Sept. 27, 1917 from "Mrs. Kraft's garden". False Blue Indigo is not a native of Minnesota as MN is northwest of its growing range. It is found in the eastern part of the U.S. In several Midwest and east coast states where the plant is native, it is endangered. The only species of Baptisia native to Minnesota are the Plains Wild Indigo, B. bracteata, and White Wild Indigo, B. alba, (named by some authorities as B. lactea), and both species are on the DNR Special Concern List.
Plant classification authors: After initial naming by ('L.)', that is, Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy, further work was done by ‘R.Br.' which is for Robert Brown (1773-1858), Scottish botanist for whom ‘Brownian motion’ is named, and who provided names and descriptions of various plant families and was the first keeper of the Botanical Dept. of the British Museum. His work was amended by ‘W.T.Aiton’ which is William Townsend Aiton (1766-1849), Scottish botanist, son of William Aiton; he succeeded his father as director of Kew Gardens, was a founder of the Royal Horticultural Society, and published a second edition of his father’s catalogue Hortus Kewensis.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"