Poa hartzii ssp. alaskana Soreng Poaceae

Poa hartzii ssp. alaskana Soreng
Synonyms: Poa alaskana
Poaceae
Global Distribution: Endemic to arctic Alaska.
Alaska Distribution: Arctic Tundra.
Ecoregions Occupied: Beaufort Coastal Plain, Brooks Range.
Conservation Status: S1S2 G3G4T1T2; BLM Sensitive.
Description 147
Panicles
narrowly
lanceolate with
branches erect
to ascending
Illustration by Sandy Long, courtesy
of Intermountain Herbarium
4 cm
2 mm
Spikelets 5
to 7 mm
long with 3
to 5 florets
Illustration by Dominique Collet
Bases of culms and
leaves distinctly red or
red-purple
Culms loosely tufted, 20
to 45 cm tall
Lemmas 5.5 to 7 mm long,
somewhat pubescent near
base, sparsely villous on keel
and marginal veins
215

Poa hartzii ssp. alaskana
General:
Leaves:
Inflorescences:
Spikelets:
Perennial grass, loosely tufted; culms 20 to 45 cm tall, usually
decumbent; bases of leaves and culms distinctly red or redpurple.
Sheaths closed for up to 1 / rd 3 of their length, bases of basal
sheaths glabrous; ligules 5 to 7 mm long, smooth or slightly
rough; blades 2 to 9 cm long, 1.5 to 3 mm wide, folded or
with margins rolled inwards, apices narrowly prow-shaped.
Panicles 7 to 12 cm long, erect, narrowly lanceolate with 7 to
40 spikelets; nodes usually with 2 branches; branches 1 to 3
cm, erect to ascending with 1 to 10 spikelets in the upper
2 / rds 3 .
Spikelets 5 to 7 mm long, 3.5 to 4 times longer than wide,
lanceolate; florets 3 to 5; upper glumes 5 to 6 mm long, often
exceeding lowest lemmas; lemmas 5.5 to 7 mm long,
somewhat pubescent near the base, margins membranous.
© Robert Soreng
Ecology
Elevation:
Usually occurs from near sea level to 20 m; known from
up to 860 m in the eastern Brooks Range.
216

Poa hartzii ssp. alaskana
Landform:
Soil Type:
Moisture regime:
Slope:
Aspect:
Vegetation type:
Associated species:
Longevity:
Phenology:
Population estimate:
Rivers bars, floodplains, active sand dunes.
Sand, silt.
Dry to moist.
Flat to gently sloped.
No particular aspect.
Sparsely vegetated.
Artemisia borealis, Festuca rubra, Leymus mollis,
Poa glauca, Rumex aureostigmaticus.
Perennial; longevity unknown.
Flowering July.
There are seven known occurrences in Alaska; the total
state population is likely several thousand individuals. 148
Reproductive biology: Poa hartzii ssp. hartzii is wind-pollinated and
apomictic. 114 However, reproductive strategies between
subspecies may differ: while Poa hartzii ssp. hartzii
rarely forms anthers, the anthers of Poa hartzii ssp.
alaskana are more well-developed. 147
Similar Species 147
Several Deschampsia and Festuca species, especially Festuca altaicai, are found
in similar habitats as and can be confused with Poa hartzii ssp. alaskana.
However, Poa hartzii ssp. alaskana lacks awns or awn-points on the lemmas. Poa
hartzii ssp. alaskana can be confused with several other Poa species that grow in
sandy riverbanks, dunes, and floodplains in arctic Alaska. These similar Poa
species can be distinguished from each other according to the morphological
differences listed in the table below.
Species
Poa hartzii ssp.
alaskana
Poa hartzii ssp.
vrangelica
Poa glauca
Poa arctica
Poa alpina
Leaf and
culm bases
Red or redpurple
Red or redpurple
Lacks red or
red-purple
bases
Lacks red or
red-purple
bases
Lacks red or
red-purple
bases
Basal Branching Spikelets Anthers
Branches emerge
from both the sides
of sheaths and the
tops of sheaths
Branches emerge
from both the sides
of sheaths and the
tops of sheaths
Branches emerge
primarily from the
sides of the sheaths
Branches emerge
primarily from the
sides of the sheaths
Branches emerge
from the tops of the
sheaths
Not
viviparous
Viviparous
Not
viviparous
Sometimes
viviparous
Uncommonly
viviparous (in
Alaska)
2.0 to
2.8 mm
long
Aborted,
usually
around
0.8 mm
long
1.8 to
2.5 mm
long
1.4 to
2.5 mm
long
1.2 to
2.5 mm
long
217

Poa hartzii ssp. alaskana
© Robert Soreng
© Robert Soreng
218