yellow giant hyssop (Agastache nepetoides)
catnip giant hyssop
yellow giant hyssop
SCIENTIFIC SYNONYMS: There are no scientific synonyms for
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name of yellow giant
hyssop is Agastache nepetoides (L.) Kuntze. The pale yellow flowers are
not very showy because they seem small in comparison to the rest of the
plant and only a few flowers are in bloom at the same time. Thus, the
attractiveness of yellow giant hyssop consists primarily of its foliage.
One other species in this genus occurs in Facquier County - Agastache
scrophulariaefolia (blue giant hyssop). Blue giant hyssop is about the
same size as yellow giant hyssop and it has a similar appearance, except
that the corolla of its flowers are blue and its stems are pubescent.
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: This native perennial plant is 4-7' tall and little branched, except
for a few stems developing from the middle to upper leaf axils. The cen-
tral stem is light green, glabrous, 4-angled, and strongly winged.
Leaves: The opposite leaves are up to 6" long and 3" across, while their
petioles are up to 2" long. The leaves are lanceolate-ovate or cordate-ovate, medium to dark green, and hairless or nearly so; their margins are coarsely serrated. At the apex of a plant, young vegetation may be slightly pubescent.
Flowers: The central stem and major secondary stems terminate in indivi-
dual spikes of flowers. Each spike is about 4-16" long and ¾1" across; the
length of each spike is highly variable depending on the size of each plant
and its maturity. The flowers are densely crowded together all around the
spike, although only a few flowers are in bloom at the same time. Each
flower consists of a tubular corolla about 1/3" long and a tubular calyx
about 1/4" long. The pale yellow corolla has 2 upper lobes, 2 lateral lobes,
and a single lower lobe that is the largest in size. These lobes are short and rounded. The light green calyx has 5 teeth and several veins along its sides;
it is hairless or mostly hairless. Each flower has 4 stamens that are strongly exerted from the corolla and a divided style. Individual flowers are short-
Fruit/Seeds: At maturity, each flower is replaced by 4 nutlets.
Roots: The root system is fibrous and rhizomatous. Vegetative colonies
are often produced from the rhizomes.
REGENERATION PROCESS: Yellow giant hyssop propogates itself
through reseeding and vegetative production from rhizomes.
HABITAT TYPES: Habitats include deciduous woodlands, woodland
borders and openings, thickets, meadows in wooded areas, and powerline
clearances in wooded areas. Occasional disturbance is beneficial if it re-
duces, but does not eliminate, the shade from canopy trees and other kinds
of woody vegetation.
SITE CHARACTERISTICS: Yellow giant hyssop prefers light shade
to partial sun, moist to mesic conditions, and a fertile loamy soil. This
plant dislikes dry sunny areas, which will cause the foliage to wilt during
a summer drought.
SEASONAL DEVELOPMENT: The blooming period occurs from mid-
summer to early fall and lasts 1-2 months.
GENERAL DISTRIBUTION: Yellow giant hyssop is a primarily a
species of the eastern United States. It extends north to southern New
England, and west through the Ohio Valley and into the eastern Great
Plains region. While it can be found in the southeast Atlantic states, it is
less common in the Gulf states, noticably absent from Alabama, Louisiana,
and Texas. It is not reported occurring in the Rocky Mountain states, south-
western states, or the far western and northwestern Pacific coast states. It
also occurs in Quebec and Ontario, but does not extend across the Canadian
prairie provinces, Rocky Mountain provinces, or Pacific coast region.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: The flowers are visited by bees (e.g.,
honeybees, bumblebees, & Halictid bees), bee flies, and butterflies. These
insects suck nectar, although some of the bees may collect pollen. Syrphid
flies also visit the flowers to feed on pollen, but they are less effective at
cross-pollination. The dense foliage of yellow giant hyssop attracts its fair
share of predatory insects, including parasitic wasps, spiders, ladybird
beetles, and others. White-tailed deer leave the foliage alone because of
its bitter taste.
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