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Montana Field Guide

Montana Field Guides

Threadleaf Beakseed - Bulbostylis capillaris

Status Under Review
Native Species

Global Rank: G5
State Rank: SU
(see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value:

External Links






State Rank Reason (see State Rank above)
Bulbostylis capillaris is documented in Montana from a 1941 Carbon County collection made by W.E. Booth; another much older, but undated "Yellowstone Valley" collection is also attributed to Montana (https://www.pnwherbaria.org/). However, the distribution of Threadleaf Beakseed includes eastern, mid-western, south-central, and California states of the U.S. (Kral in Flora of North America [FNA] 2002). Plants have not been documented in our neighboring states (Kral in FNA 2002; http://bonap.org/). It is possible that the Montana collection(s) is from an introduced population (Lesica et al. 2012) that has not persisted. Threadleaf Beakseed in Montana is assigned as unrankable (SU) due to a lack of current information and scanty historical data.
 
General Description
PLANTS: Erect, tufted (cespitose) annuals that grow from 5-15 cm, but may reach 30 cm in other states. The bases are soft. Sources: Lesica et al. 2012; Kral in FNA 2002.

LEAVES: Thread-like (filiform) leaves grow at the base or along the stem, about 0.5 mm wide and involute. Sheaths are ciliate at their upper end and their borders are tan. Ligules are absent. Backs of the leaves are prominently ribbed and glabrous. Sources: Lesica et al. 2012; Kral in FNA 2002.

INFLORESCENCE: Terminal with several spikelets borne in an umbrella-like arrangement. A few leaf-like bracts occur below the inflorescence. Spikelets are red-brown, narrowly ovoid, 3-5 mm long with spirally arranged flowers. Sources: Lesica et al. 2012; Kral in FNA 2002.

Phenology
Plants fruit from summer to fall (Kral in FNA 2002).

Diagnostic Characteristics
A technical key is needed to differentiate members of the Sedge (Cyperaceae) Family:

Bulbostylis capillaris - Threadleaf Beakseed
*Achene: Naked (not inside a perigynium). Bristles are lacking. Achene is surrounded only by scales.
*Bracts: Directly below the inflorescence the bracts are leaf-like.
*Spikelets: Ovoid and occur in an umbrella-like inflorescence. Scales are arranged in spirals.

Trichophorum
*Achene: Naked (not inside a perigynium). Bristles are lacking. Achene is surrounded only by scales.
*Bracts: Directly below the inflorescence the bracts are leaf-like.
*Spikelet: Ovoid and solitary at the top of the stem. Scales are arranged in spirals.

Cyperus
*Achene: Naked (not inside a perigynium). Bristles are lacking. Achene is surrounded only by scales.
*Spikelets: Mostly flattened. Scales are arranged opposite of each other.

Lipocarpha
*Achene: Naked (not inside a perigynium). Bristles are lacking. Achene is surrounded only by scales.
*Bracts: The inflorescence appears lateral on the stem. The main bract is erect and stem-like.
*Spikes: Ovoid. Scales are arranged in spirals.

Range Comments
Widespread but highly sporadic across much of North America; more common in the east and nearly entirely absent from Rocky Mountains and Great Basin regions (Kartesz 2009).

Observations in Montana Natural Heritage Program Database
Number of Observations: 2

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Prairie, sandy outcrops, and gravelly waste areas (Kral in FNA 2002). In Montana Threadleaf Beakseed has been found on a sandy bench in the Valley zone (https://www.pnwherbaria.org/).

Reproductive Characteristics
FLOWERS
Perfect, consisting of an ovate scale, about 2 mm long, 1 or 2 anthers, and 1 ovary with a 3-parted style. The scale is both notched and awned at the tip.

FRUITS
Achenes: yellowish, 3-sided, 1 mm long, and transversely ribbed. The style persists on the fruit as a buttonlike tuberacle.

Threats or Limiting Factors
Threats to Threadleaf Beakseed have not been identified.

References
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Citation for data on this website:
Threadleaf Beakseed — Bulbostylis capillaris.  Montana Field Guide.  .  Retrieved on , from