Fritillaria
ayakoana
has one of the most limited ranges of all the Japanese endemic Fritillaria and is known from only two
areas of Shimane Prefecture in southern Honshu. It was discovered in
1974 by Ayako
Maruyama, the wife of a local botanist, in Sada-cho near Izumo-shi in
the north
of the prefecture. The location is about 50 km north of F.
amabilis in neighbouring Hiroshima prefecture. In 1979 Iwao
Maruyama and Naohiro Naruhashi
described F. ayakoana as a new
species as it
differed from F. amabilis in its
flower shape and nectaries. F. amabilis
has a narrow-campanulate flower and the tepal apex is rounded. In
contrast F. ayakoana has a more
open cup-campanulate
flower with a pointed tepal apex. This is only evident in the middle of
its
flowering period and otherwise appears much closer to F.
amabilis. The difference in the nectaries is therefore the
key
diagnostic character. In F. amabilis
the nectary is small and circular at the base of the tepal while in F. ayakoana it is about 2 mm from the
base of the tepal and 6-11 mm long.
The
type locality for F.
ayakoana has been lost through the construction of a new road
but two small
populations remain in Sada-cho. Both are located in residential areas
about 2
or 3 km apart but with less than 100 flowering plants between them. In
recent
years a second cluster south of Sada-cho has been found from Kawamoto
to Ohda
with one population located as recently as 2007. At Kawamoto the
population is
actively managed and protected by the local community. Each year in
March
special weekend viewing days and lectures are organised for wildflower
enthusiasts. The total size of the Kawamoto population is probably
equal to the
total population from all other known sites.
Geography and disribution
The Chūgoku region
in south-west Honshu is characterized by
two distinct climatic zones. North of the Chūgoku Mountains most of the
land is
formed by irregular hills with the exception of the rice fields of the
Izumo plain.
Facing the Sea of Japan the weather is colder and wetter, often with
snow
extending into early spring. The area is known as San-in
or ‘In the shade of the mountain’. To the south of
the
Chūgoku Mountains the land slopes away to the Seto Inland Sea. Known as
San-yo
or
‘Sunny side of the mountain’ the land is protected
from the north by the
mountains and to the south by the island of Shikoku. The weather here
is milder
and calmer with less rain.
Three
Japanese endemic Fritillaria
are found within the
Chūgoku region and all occurring in different biogeographic zones. All
three
also have 11 and not usual 12 chromosomes found in most Fritillaria. To the
south-east of the mountains and at lower elevations are pockets of F. japonica.
Usually at higher elevations but still to the south of the mountains
and
running throughout the region is
F. amabilis. To the north of the mountains between
the Gonokawa River in the west and the Izumo Plain in the east F. ayakoana can
be found from near sea level up to almost 800 m. Most F. ayakoana grow on
land that
has been altered by human activity except for several small pockets on
Mt
Ooetakoyama. Growing in bamboo scrub below deciduous tree this is
possibly all
that remains of its natural habitat. A field census on Mt
Ooetakoyama in 2008 recorded just 26 flowering plants across four
locations.
Cultivation
Although Fritillaria ayakoana
is rare in cultivation it is
not difficult to grow. Use equal parts of composted bark, leaf mould
and fine
grit in terracotta pots. Plunge in an open frame away from direct
sunlight. The
bulbs must be kept moist at all times. As F. ayakoana
flowers in late winter
hand pollinate to encourage seed set. Seed output recorded in
cultivation from hand pollinated plants was in the ranges 10 -
40
seeds per capsule (average 25 seeds). The output from Mt Ooetakoyama
plants was
only in the range 10 - 13 seeds per capsule.
Description
Fritillaria
ayakoana
Maruyama & Naruhashi, the Journal of Geobotany, 26 (4):
92(1979).
Bulb
10-15 mm in
diameter, white twin scaled covered in a
thin translucent tunic. Stem slender, smooth, height 10-15 cm topped by
a whorl
of 3 leaves with 2 opposite leaves 1-20 mm below. Leaves green,
occasionally
red, all narrow lanceolate or linear, opposite pair 40-80 x 7-15 mm,
whorled
leaves 30-65 x 3-10 mm. Pedicel 6-13 mm long, emerging from the middle
of the
whorl of leaves, green, grey or dark pink, often wrinkled. Flowers
nodding
cup-campanulate, white with pink or purple-brown longitudinal veining.
Tepals
entire up to 29 mm long, inner 9 mm, outer 8mm wide, apex
pointed. Nectaries about 2 mm from the base of the tepal, a
green
dot with pale yellow streak towards the apex, 6-11 mm
long. Filament thin, papillose up to 11 mm long. Anthers
narrow oblong to 6 mm long, pale yellow-brown. Style papillose, white,
sometimes with pink dots, to 10 mm long, apex divided 1-1.5 mm. Capsule
green, nodding,
pyramidal with a concave base 10-16 mm long, 7-11 mm wide. Seed ovoid,
not
winged with an elaiosome. 2n = 22.
Japanese Name: イ
ズモコバイモ (Izumo-kobaimo)
Habitat:
below deciduous tree, with Asarum
asperum F. Maek., Corydalis
lineariloba Siebold & Zucc., Epimedium sempervirens
Nakai. & F. Maek., 50-800 m.
Flowering period: March to early April.
Type:
Japan, Honshu, Shimane, Hikawa-gun, Sada-cho. I
Maruyama, N Naruhashi et. T Sato No. 1, 28 March 1978 (KYO!).
Shimane
Red Data Book 2004: Extermination fear I type CR+EN
