|Adoxaceae - Town-hall Clock
Adoxa moschatellina (Moschatel, Moscatel, Town-hall Clock,
Good Friday plant, Muskroot) is a curious plant of
woodlands, hedges and mountain ledges. The inflorescence
typically bears five flowers arranged in a cube, like the faces
of a town-hall clock. The majority of the inflorescences have
the following arrangement:
Four lateral (sideways facing) five-petaled (five equal petals,
pentamerous) flowers, each with 3 short bracts (sepals?)
behind the petals, and five stamens which fork at the base of
their filaments to give the appearance of ten stamens and
five stigmas with prominent styles (5 carpels). Each
half-stamen has a single locule (pollen-containing cavity)
inside the anther and each half dehsices (drys and splits
open) to release pollen. Each flower has one petal
uppermost and the side petals of neighbouring flowers may
The fifth terminal flower usually has 4 equal petals
(tetramerous, in 99% of cases), 2 bracts, 4 stamens which
branch to give the appearance of 8 stamens, and four styles
and stigmas (4 carpels). This flower faces directly upwards.
Such a compact arrangement of parts requires well-timed development to prevent the five flowers from
obstructing one-another or forming a chaotic tangled mass. Anthesis (flower-opening) occurs on the
inflorescence from the top downwards, with the terminal flower opening first (cf. terrestrial orchids in which
the basal flowers generally ripen first and the terminal flowers last). The petals are green when newly
opened, turning pale yellow later. The styles are structurally mature at anthesis. All the petals of the
terminal flower open together. The anthers of the terminal flower dehisce about 2.5 days (2-7 days) later.
Then two of the lateral flowers on opposite sides of the cube open about 3 (-6) days after the terminal
flower opens. They open their topmost petals first, then the upper pair of lateral petals, followed by the
lower pair of lateral petals. Then the remaining pair of lateral flowers open.
Within about 2 weeks of anthesis, the petals turn from green to yellow and
after a further 2-3 weeks they turn papery and close over the ovaries.
When the flowers are newly opened and the petals green, the yellow
anthers stand out like the numbers on a clock face (except there are only
10 of them!).
The aerial parts of the plant appear in late January. The inflorescence
soon starts to develop from the axil between two leaves. The basal leaves
are long-stalked and 2-3 ternate (divided into three segments 2 or 3 times)
meaning that each leaf is a compound leaf divided into three leaflets, each
of which is further subdivided into three secondary leaflets which may be
similar subdivided a third time. The flowering stems (inflorescences) may
reach 15 cm (6 inches) in height and bear a further pair of leaves which
are once ternate (each divided into three leaflets).
Moschatel is pollinated by flies (Diptera) and night-flying moths. Flies don't
make much use of colour when foraging, so fly-pollinated plants are often
yellow-green in colour. At the base of each petal (inside the petal or
corolla tube) on its upper (adaxial) surface is a group or cushion of 20-30
short-stalked or sessile (stalkless) and clavate (club-shaped) multicellular
trichomes (hairs). These are glandular and secrete the nectar which is
sometimes visible inside the corolla. The plant also has a faint musk-like
odour. The rhizome and stolons smell like musk.
The ovaries of each pollinated flower unite to form a single drupe-like fruit with the sepals (calyx) still attached.
Germination is epigeal (the cotyledons appear above ground and photosnythesise). Creeping stolons root at
intervals to produce new plants (cloning). Each plant has a short whitish rhizome which puts out new shoots
each January. The terminal flower opens around mid-March and in mid-May the rhizomes and stolons grow
extensively. In April the stalks of the leaves corkscrew down to the ground and by mid-June no plant remains
are visible above ground. Some plants may, however, flower as late as May. The plant is perennial, surviving
as a subterranean rhizome (short, white and scaly) until the following winter when the cycle repeats.
Only about 55% of moschatels are reported to have the typical inflorescence form just described. The lateral
flowers are the most variable and some inflorescences may have as few as 2 or 3 flowers or as many as 10,
though almost 90% have five flowers. Other variations occur in the number of petals. The terminal flower
sometimes has five petals or occasionally only 3, and one or more of the lateral flowers may have only 4 petals.
Holmes, D.S. 2005. Sexual reproduction in British populations of Adoxa moschatellina L. Watsonia 25: 265-273.
Whitehead, H. 1902. Variation in the Moscatel (Adoxa Moschatellina L) Biometrika 2: 109-113.
30 April 2016