Skip to main content

Plant Fact Sheet

PURPLE GIANT


HYSSOP

Agastache scrophulariifolia


(Willd.) Kuntze

Plant Symbol = AGSC


Contributed by: USDA NRCS Cape May Plant Materials

Center


USDA-NRCS PLANTS Database / William S. Justice @ USDA-NRCS

PLANTS Database


Alternative Names

Common Alternate Names:

giant hyssop

prairie hyssop


Scientific Alternate Names:

Hyssopus scrophulariifolia Willd.

Agastache scrophulariifolia var. mollis (Fernald) A.

Heller


Uses

Wildlife Use: Purple g iant hyssop provides a nectar source

for pollinators and is well suited for use in pollinator

restoration habitat. Preliminary observation found that

purple giant hyssop attracted 14 different species of

Hymenoptera and Lepidoptera in Cape May, New Jersey.

The halictid bee (Agapostemon virescens), leaf-cutter bee

(Megachile mendica), and Megachile texana species were

most frequently observed visiting the flower. Other bees

known to frequent the flower are the European honey bee

(Apis mellifera), black and gold bumble bee (Bombus


auricomus), and Bombus pensylvanicus. The flower also

attracts goldfinches and hummingbirds.


Ornamental

Purple g iant hyssop is a popular ornamental p lant. The

relatively large height of the plant makes it a good choice

as a background against fencing.


Status

Please consult the PLANTS Web site and your State

Department of Natural Resources for this plant’s current

status (e.g., threatened or endangered species, state

noxious status, and wetland indicator values).


Description and Adaptation

Description: Purple giant hyssop is a late-flowering,

native perennial herb of the mint family. It can grow

unusually tall for a mint; up to 6 feet, with diamond-

shaped stems, aromatic foliage and flowers, and vigorous

stolons. The stems are erect and form clumps. The upper

braches may be purplish.


The densely branched inflorescence is a 1–6 in terminal,

continuous, or interrupted flower spike, o r raceme. The

plant usually has several spikes. The tops of the spikes

develop into a flower and two lateral branches develop

under the flower from a common node; giving the

inflorescence a symmetrical appearance. The flower

clusters persist throughout the winter.


The individual flowers are ¼ in long, 15-nerved tubes that

are lavender to pale p ink. The upper lip has 2 lobes and

projects forward; and the lower lip curves downwards

with 3 lobes. The individual lobes are 3-nerved.


Not all flowers open at the same time. The flowers

contain 4 stamens that extend beyond the flower. The two

lower stamens curve upwards, while the two upper

stamens curve downwards. The pollen sacs are nearly

parallel.


A. scrophulariifolia is similar to blue g iant hyssop (A.

foeniculum), however purple giant hyssop has a cup-like

whorl o f green sepals (modified leaf-like bracts under the

flower) while A. foeniculum has blue-violet sepals. Often

the sepals of giant purple hyssop have colored marg ins.


Nutlets are .05-.07 in (1.5–2 mm), dark brown, rounded,

and minutely hairy at the squared-off tip.


The stalked leaves of purple giant hyssop are positioned

opposite on either side of the stem. The sharp-pointed

leaves are 4 in long and 2 in wide, with a cordate,

somewhat heart-shaped or rounded base. The margins of

the leaves are coarsely toothed and short hairs cover the

leaf stems. The undersides of the leaves are green, and


smooth or appear shaggy. Conversely, the underside of

the blue giant hyssop (A. foeniculum) is whitish. The

species name is derived from the Scrophulariaceae or

figwort family, for the resemblance of the leaves to the

figwort. When crushed, the leaves emit a distinct, anise-

like odor.


Purple giant hyssop distribution from USDA-NRCS PLANTS Database.


Adaptation: Like many members of the mint family,

purple giant hyssop grows best in moist soil or wet

conditions. It is found in rich woodland sites with dappled

shade, woodland borders, meadows, thickets, the upper

limits of floodplains, and upland woods. It prefers

recently disturbed, sandier soils where competit ion is

limited. Plants will not persist under hot and dry

conditions (USDA zone 9 or higher). Threats to its habitat

include changes in land use, competition from non-native

species, and natural succession. For updated distribution,

please consult the Plant Profile page for this species on

the PLANTS Web site.


Es tablishment

Purple g iant hyssop requires cold stratification and

sunlight to germinate. Keep the seed for 8 weeks at 40ºF

and move to 68ºF for germinat ion. The seeds will

germinate in 30–90 days in containers with good

drainage. When planting in the fall, cold stratification is

not required. For vegetative propagation, take late spring

cuttings from the basal growth that emerges in mid-

March. These cuttings can be fertilized for quicker

establishment.


Purple g iant hyssop propagates rapidly by seed and

transplants easy into natural settings. One can use it in

dry-site seed mixes for pollinator habitat at 8% of the

mix. Sow into open ground and cover with a light layer of

mulch or sow into flats and grow to 12 in (30 cm) in


height before transplanting. There are 60,000–93,000

seeds/ounce.


Management

Because purple giant hyssop requires soil disturbance for

successful establishment, regular clearings must be

created and maintained through tree-thinning, elimination

of competing vegetation, or by delaying natural

succession cycles.


Populations of purple giant hyssop tend to be short-lived

because they are easily out-competed. Therefore, field

plots may need to be re-established every 3–4 years for a

fuller look. To encourage more vigorous growth, cut 2–6

in from the plant.


Pests and Potential Problems

Little is known about potential pests. Anecdotal evidence

suggests it can be affected by mildew and rusts. There are

mixed findings on the plant’s susceptibility to browsing

deer.


The gradual and continued loss of farmland to either

forests or urbanization continues to threaten a species that

requires open fields and meadows for habitat.


Environmental Concerns

None


Prepared By

Christopher M. Sheahan; USDA-NRCS, Cape May Plant

Materials Center, Cape May, New Jersey.


Citation

Sheahan, C.M. 2012. Fact sheet for purple g iant hyssop

(Agastache scrophulariifolia). USDA-Natural Resources

Conservation Service, Cape May Plant Materials Center.

Cape May, NJ. 08210.


Published 07/2012


Ed ited:


For more information about this and other plants, please

contact your local NRCS field office or Conservation

District , and visit the

PLANTS Web site or the Plant

Materials Program Web site
materials.nrcs.usda.gov>


US DA IS AN EQUAL OPPORTUNITY PROVIDER AND EMPLOYER


http://www.nrcs.usda.gov/
http://plants.usda.gov/
http://plant-materials.nrcs.usda.gov/
http://plant-materials.nrcs.usda.gov/


Plant Fact Sheet

PURPLE GIANT

HYSSOP

x

Please add some content in Animated Sidebar block region. For more information please refer to this tutorial page:

Add content in animated sidebar