Smelowskia johnsonii G.A. Mulligan
Brassicaceae
Global Distribution:
Endemic to Alaska.
Alaska Distribution:
Arctic Tundra.
Ecoregions Occupied:
Brooks Foothills (Lisburne Peninsula).
Conservation Status:
S1 G1; BLM Watch.
Description186, 187
4 mm
Fruits arranged on
all sides of stems
Fruiting 5 to 6
mm long, 2 to 3
mm wide
Basal leaves entire or
3 toothed at tip
Plant covered in densely
silvery pubescent simple
hairs throughout
Simple caudex
Illustration by Matthew L. Carlson
299
Smelowskia johnsonii
General:
Perennial herb from simple caudex; entire plant densely
covered in short, white hairs; stems several from base,
unbranched or branched above, 4 to 16 cm tall.
Leaves:
Petioles 8 to 13 mm long; basal leaves oblanceolate to
spatulate, 8 to 18 mm long, 3 to 7 mm wide; margins entire,
3-toothed at leaf apex, or palmately lobed; apexes densely
covered with long, simple, silver hairs; stem leaves subsessile
and reduced upwards.
Flowers:
Flowers arranged in compact racemes elongating in fruit;
sepals 3 to 3.5 mm long; petals lavender to purple, obovate, 4
to 5 mm long, 3 to 4 mm wide.
Fruits:
Fruiting pedicels ascending (often forming less than 40° angle
with stem), straight, 11 to 27 mm long; fruits ellipsoid to
obovoid, 5 to 6 mm long, 2 to 3 mm wide; styles 0.2 to 0.3
mm long.
2 mm
ALA 138042
300
Smelowskia johnsonii
Ecology
Elevation:
Known from near sea level to 620 m.
Landform:
Alpine slopes, alpine ridges.
Soil Type:
Talus, scree, unconsolidated rubble; associated with
calcareous substrates.
Moisture regime:
Dry.
Slope:
Gentle to steep.
Aspect:
No particular aspect.
Vegetation type:
Sparsely vegetated.
Associated species:
Chrysosplenium wrightii, Cystopteris fragilis,
Papaver mcconnellii.
Longevity:
Perennial, likely long-lived as some specimens show
very thick, well-developed caudexes.
Phenology:
Flowering June through late July; fruiting mid-July
through August.
Population estimate:
There are three occurrences in Alaska, none of which
have been revisited since 1962; population sizes
unknown.
Similar Species186, 187
Smelowskia johnsonii can be distinguished from all other Smelowskia species,
including those in the table below, by the presence of dense, silver pubescence on
the leaves, with hairs primarily simple and 1 to 1.8 mm long. Several other
Smelowskia species are known from Northwest Alaska and can be confused with
Smelowskia johnsonii. These species can be distinguished by the morphological
characteristics described in the table below.
Species
Smelowskia
johnsonii
Smelowskia
borealis
Smelowskia
porsildii
Leaves
Densely
covered with
silver, simple
hairs 1 to 1.8
mm long
Densely
covered with
dendritic hairs
and fewer
simple hairs
up to 1 mm
long
Densely
covered with
gray, dendritic
hairs and
fewer simple
hairs up to 1
mm long
Inflorescences
Petals
Fruits
Flowers and
fruits arranged
on all sides of
stems
Lavender to
purple
5 to 6 mm long,
2 to 3 mm wide
Flowers and
fruits arranged
on one side of
stems
Lavender to
purple
12 to 28 mm
long, 4 to 8 mm
wide
Flowers and
fruits arranged
on all sides of
stems
White
6 to 10 mm
long, 1.5 to 2.5
mm wide
301
Smelowskia johnsonii
2 mm
ALA 133269
302