Rodgersia are exceptional plants for the garden. They are true giants that will make a statement which your visitors will remember for quite some time. The problem with this genus is that the species are fairly similar to one another and this has resulted in many misidentified pictures on the internet.  In this blog post I hope to provide a simple way to help you identify your plants.

Rodgersia Introduction

Rodgersia is a genus of architecturally significant, large leafed plants belonging to the Saxifragaceae family. There are currently 5 accepted species and dozens of named clones.

Rodgersia podophylla is native to Japan and Korea and the other species are found in China, Tibet and Nepal. In native habitats they grow along streams in shady woodlands.

Rodgersia flower in mid-summer producing large flowering stems that rise above the foliage. The astilbe-like panicle of flowers are spectacular and in some varieties can reach 2 feet above the plant. Flower color ranges from white, yellow to pink and red. All species are apetulous (no petals) and the flower color is provided by the sepals and stamens. All species have 2 carpels, and Rodgersia podopylla and Rodgersia pinnata have 10 stamens (# stamens in other species unknown).

Even though the flowers are significant, most people grow the plant for the leaves. The leaves are large, and strongly textured. Newly forming leaves can be bronze, copper or metallic colored and in some varieties this color remains as the leaf matures. The leaves have strong stems that can be up to a meter in length. They hold the leaves up well, even in a windy condition, although strong winds may tear the leaves. In fall, the leaves of some species and cultivars can turn a nice coppery-brown color.

Rodgersia tabularis was at one point part of the genus, but it has now been moved into its own genus, and called Astilboides tabularis. It is not discussed further in this report.

Rodgersia Culture

Plants prefer a semi-shade location which has rich, moist soil. They will grow in full sun provided they have enough soil moisture. The leaf edges will turn brown if they get too dry. Plants will be smaller and grow more slowly in less than ideal situations, but even in these conditions Rodgersia make impressive specimens.

Plants are hardy in zones 4-9, but new spring growth can be damaged by an early frost. Once a plant is established it will recover from such  frost damage and grow new leaves as if nothing had happened.

Thick rhizomes spread just under the surface of the soil. They are mostly clump forming, but Rodgersia nepalensis and some forms of Rodgersia podophylla have a tendency to spread. All of the large leafed varieties create impressive plants in a few years.

Rodgersia can be propagated by seed or by spring division of the rhizome.

Rodgersia Identification Key:

The identification of Rodgersia is complicated by a number of factors:

a)      All of the species interbreed easily. Plants grown from seed where more than one species or cultivar is grown has a good chance of being a hybrid. Too many times these seeds are incorrectly labeled with a species name.

b)      Many of the pictures on the internet are identified incorrectly. Even prominent plant information sites such as the Encyclopedia of Life have incorrect pictures posted.

c)       Leaves on a single plant can vary. Young leaves can be different than leaves produced later in the season. Leaves on seedlings may not look like those found on mature plants and therefore seedlings need to be grown for a couple of years before you can be sure of the leaf type.

d)      Rodgersia pinnata is a very diverse species and at times its leaves can look like that of other species.

Single plant purchased as Rodgersia pinnata var. Superba showing a variety of leaf types;

(A) almost palmate, (B) pinnate and (C) pseudo pinnate

There are five or six species of Rodgersia, depending on the current taxonomic climate. Currently, Rodgersia henrici is considered to be a variety of Rodgersia aesculifolia and that is the format followed here.

Rodgersia species can be identified primarily from their leaf shape, with some clarification provided by flower color. They have compound leaves of two general types:

•  Palmate-several leaflets radiating out from a central point, similar to a horse-chestnut.

•  Pinnate-leaflets arranged in pairs along a central rachis.

The following plant key can be used to identify species. It may be helpful to know that Rodgersia sambucifolia and Rodgersia nepalensis are fairly rare in cultivation.

1a. Leaves are palmate.

2a. Leaflets have an ovate shape……………………………………..R. aesculifolia

2b. Leaflets have 3-5 shallow lobes near the apex, resembling a ducks webbed foot .……………………………………………………………………………………R. podophylla

 1b. Leaves are pinnate

3a. leaves are more pseudo pinnate than true pinnate, with one group of leaflets near the apex and another group of leaflets near the base of the leaf. At times the rachis is so compressed to almost disappear, making the leaf look more palmate than pinnate ….…R. pinnata

3b. leaves are true pinnate with leaflets more or less equally spaced along the rachis

4a. flowers are white………………………………………………………….…….R. sambucifolia

4b. flowers are green or yellow……………………………………….…..…….R. nepalensis

Rodgersia aesculifolia

rod-JER-zee-ah ess-kew-lih-FOE-lee-ah (tetraploid 2n=60)

The leaves of Rodgersia aesculifolia look very much like a horse-chestnut (Aesculus) leaf. It is symmetrically palmate with obvate leaflets that are coarsely serrated. The leaflets do not have petioles. The flowers are white, white tinged pink, or a definite pink color. It is commonly called the Fingerleaf Rodgersia.

The leaves of this Rodgersia tend to be more green than other species, but some clones do have a copper metallic sheen.

Rodgersia henrici was listed as a separate species at one time, but it is now considered to be a variety of Rodgersia aesculifolia. In researching for this report it became clear that the experts don’t agree on what the differences are between the two species. The following is a list of features that have been reported, but not a single source of information includes all of the differences. The differences may or may not be valid and are documented here only to show the complexity that exists.

Rodgersia purdomii is now considered to be a group within Rodgersia aesculifolia.

Feature	Rodgersia aesculifolia	Rodgersia aesculifolia var. henrici
Flower diameter	2-8 mm	8-18 mm
Bud color	White, yellowish or pink	pink
Flower color	White/green or white tinged with pink, aging to green	Pink, color deepens as flowers age
Inflorescence	Airy	Not airy, multiple tiers of flowers, which are closely packed
Leaf texture	Tends to deflects down at the mid-vein and the apex	Firm, with no tendency to deflect down
Veins	Smooth upper surface, only main veins are prominent on the underside of the leaf	Sunken, giving top of the leaf a quilted effect, prominent on the underside of the leaf
Number of leaflets	6-7	7-9
Pubescence	Underside of leaf and petiole is Pubescent	Pubescent only on the veins
Sepals	Enlarge after fertilization	Don’t enlarge after fertilization

Rodgersia aesculifolia is a large plant that can grow to 2 m (6 ft), but is normally 1.5 m (4.5 ft) tall. It is the largest Rodgersia and may be hardy to zone 3, but definitely zone 4.

Cultivars:

Big Mama – usually has 7 leaflets, 4 feet tall, pink flowers

Irish Bronze – highly textual, glossy bronzed leaves, cream flowers, height 90 cm (36”), awarded AGM

Werner Muller – commonly listed as R. purdomii, dark green leaves, white to light pink flowers

Rodgersia podophylla

Rod-JER-zee-ah poe-doe-FIL-lah (diploid 2n=30)

The leaves of Rodgersia podophylla are palmate, consisting of 5-7 leaflets. The leaflets are jagged at the tip with 3-5 lobes, resembling a duck’s webbed foot. The leaves can be thick and leathery, or thinner. The former tends to show more bronze color in spring and fall.

The flowers are creamy-white in foot long clusters and sepals age to green. This species can be shy to flower.

More than other Rodgersia, this species needs protection from too much sun.

Cultivars:

Braunlaub – dark bronze spring leaves, dark green in summer, good fall color, creamy-white flowers

Pagode – bronzed spring growth, dark reddish fall color, very floriferous, creamy-white flowers

Parasol – bronze-tinted spring leaves with white flowers

Rotlaub – dark red spring leaves, dark reddish fall color, holds color well in summer, creamy-white flowers

Smaragd – semi-dwarf with bright deep green leaves, creamy-white flowers

Rodgersia pinnata

Rod-JER-zee-ah pin-NAY-tuh (tetraploid 2n=60″)

Rodgersia pinnata has the most diverse leaf form of any of the Rodgersia, and this leads to regular misidentification. The leaflets are rarely arranged in a true pinnate format with evenly spaced leaflets. It is common to see some leaflets bunched at the base of the rachis, and a second bunch at the tip, with a total of 6-9 leaflets. The rachis can be of varying length, and can be so short as to almost disappear, making it look palmate.

Foliage turns a reddish-bronze in fall.

The flowers range in color from white to pink to deep claret. Each flower has 10 stamens and 2 styles. Seed heads can range from green to deep mahogany.

Rodgersia pinnata hybridizes readily with other species, extending the variability in cultivars. It grows naturally in dry grassy areas, which makes it a better choice than other Rodgersia for dry sunny garden locations.

Varieties (usually listed as cultivars):

Alba – bright green leaves and white flowers

Elegans – dark green bronze tinted leaves, leaflets heavily serrated, pale pink flowers. It may be a hybrid.

Superba – many plants with this name in culture are incorrectly named. The true variety has rich pinkish red flowers, bronze tinted spring leaves, red stems

Cultivars:

Cally Salmon – salmon pink flowers with red tinted foliage

Chocolate Wings – dark purple-bronze leaves that retain the color all summer, dark red buds, red/pink flowers. Smaller than the species.

Die Schone – dark pink flowers and very dark bronzed leaves

Fireworks – cherry-red flowers and bronzed spring foliage, smaller in all respects

Hercules – bronze foliage, pink flowers

Maurice Mason – reddish flowers with bronzed spring foliage

Rodgersia sambucifolia

Rod-JER-zee-ah sam-boo-ki-FOH-lee-uh (tetraploid 2n=60″)

The leaves are true pinnate and remain green throughout their life. The number of leaflets varies with the habitat and age of the plant, up to 13. It is very reminiscent of Sambucus Canadensis.

It is the smallest Rodgersia, reaching 60 cm (2 feet) tall, with small white flowers rapidly aging to brown-green.

Cultivars:

Mountain Select – green leaves, white flowers, red seed heads persist all summer

Redskin (Rothaut) – more vigorous than some clones, new growth brownish-red

Rodgersia nepalensis

Rod-JER-zee-ah nay-paw-LEN-sis

Rodgersia nepalensis has true pinnate leaves. The flower sepals are pale green to pale yellow.

Other Cultivars:

Blickfang

Bloody Mary

Buckland Beauty

Crug Cardinal

Die Stolze

Donard

Gilgamesch

Ideal

La Blance

Red Dawn

Richard Lee

Rubra

Comments:

1)      Pictures are taken by and are the property of Robert Pavlis, unless indicated differently

2)      Cultivar/variety names on pictures are based on the name received with the plant. It is difficult to confirm these names.

3)      If you have additional information about Rodgersia, please contact the author through the comments below.

References:

1) Rodgersia: http://flora.huh.harvard.edu/china/PDF/PDF08/RODGERSIA.pdf

2) Herbaceous Perennial Plants – Rodgersia: http://books.google.ca/books?id=zQXHjuqht40C&pg=PA857&lpg=PA857&dq=rodgersia+flowers+no+petals&source=bl&ots=vKlTOlaIw8&sig=hglQtY6mZHy2Vv43ltK_4yX6CEY&hl=en&sa=X&ei=LOfnU4L5N4OnyASY2IK4Cg&ved=0CB4Q6AEwAA#v=onepage&q=rodgersia%20flowers%20no%20petals&f=false

3) The Saxifrage Society: http://www.saxifraga.org/plants/saxbase/searchtaxa.asp?FullName=&GenusID=1053

4)    “The Explorer’s Garden” by Daniel J. Hinkley, Timber Press, 1999