Flora of North America species comparison

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Juncus arcticus

Juncus triformis

arctic rush

long-style dwarf rush, Yosemite dwarf rush
Habit Herbs, perennial, 2–10 dm. Herbs, annual, cespitose, 0.5–1.5 dm.
Rhizomes

long- creeping.

Culms

erect, 1–3 mm diam.

2–80, capillary, 0.1–4 mm diam.
Cataphylls

several.

Leaves

blade usually absent (present in var. mexicanus).

1/5–1/3 height of plant.
Inflorescences

lateral, 3–many-flowered, loose to congested;

primary bract barely exceeding to many times longer than inflorescence.

headlike clusters, each with 1–7 flowers, bracts subtending inflorescence 2–10, ovate to broadly lanceolate, inconspicuous, 0.7–2.4 mm, membranous, apex acute.
Flowers

variously pedicellate;

bracteoles membranous;

tepals chestnut brown or paler, lanceolate, (2.5–)3.3–5.5(–6) mm, margins clear;

inner series loosely subtending capsule at maturity; usually slightly shorter, margins scarious to clear, apex acutish to obtuse;

stamens 6, filaments 0.2–1.1 mm, anthers 0.9–2.2 mm;

style 0.9–1.5 mm.

tepals reddish with green central band, linear to lanceolate, 1.9–4.5 × 0.5–1.1 mm;

inner series slightly longer than outer, apex acuminate to attenuate;

stamens 3, filaments 0.4–1.1 mm, anthers 1–2.2 mm;

style persistent, 1–3.2 mm, stigma 0.5–2.5 mm.
Capsules

3-locular or infrequently pseudo-3-locular, oblate to narrowly ovoid, 3.5–4(–4.5) mm, equal to or exceeding perianth.

reddish, 3-locular, ovoid to ellipsoid or oblate, 1.6–2.5 × 1.1–1.8 mm, usually 1/2 length of tepals.
Seeds

dark amber, oblate to ellipsoid, 0.6–0.8 mm.

nearly globose to ellipsoid, 0.3–0.7 mm.
n

= 18.

Juncus arcticus

Juncus triformis
Phenology Flowering and fruiting spring–mid summer.
Habitat Shallow soil of seepage areas on granite outcrops, such as along stream banks, ditches, around springs
Elevation 0–2500 m (0–8200 ft)
Distribution
from FNA
AK; AR; AZ; CA; CO; DE; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; ND; NE; NH; NM; NV; NY; OH; OK; OR; PA; SD; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; NU; ON; PE; QC; SK; YT; Mexico; South America; Asia
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Numerous entities have been circumscribed and recognized at various nomenclatural ranks by a plethora of authors addressing state or regional floras. In considering the Juncus arcticus-balticus complex as a whole in North America, one is soon confronted with a wide-ranging and obviously polymorphic complex that has not read the literature. It is abundantly clear that the systematics of the group will not be solved on the basis of morphology alone and that resolution of the problem is ripe for molecular investigations.

Varieties 3 7 (3 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Anthers about as long as filaments; blades absent
var. alaskanus
1. Anthers at least 2 times as long as filaments.
→ 2
2. Blade-bearing leaves absent
var. balticus
2. Distal 1 or 2 leaves with obvious blade
var. mexicanus
Source FNA vol. 22. FNA vol. 22.
Parent taxa Juncaceae > Juncus > subg. Genuini Juncaceae > Juncus > subg. Graminifolii
Sibling taxa
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
J. acuminatus, J. acutiflorus, J. acutus, J. alpinoarticulatus, J. anthelatus, J. arcticus, J. articulatus, J. biglumis, J. bolanderi, J. brachycarpus, J. brachycephalus, J. brachyphyllus, J. brevicaudatus, J. bryoides, J. bufonius, J. bulbosus, J. caesariensis, J. canadensis, J. capillaris, J. capitatus, J. castaneus, J. chlorocephalus, J. compressus, J. confusus, J. cooperi, J. coriaceus, J. covillei, J. debilis, J. dichotomus, J. diffusissimus, J. drummondii, J. dubius, J. dudleyi, J. effusus, J. elliottii, J. ensifolius, J. falcatus, J. filiformis, J. filipendulus, J. georgianus, J. gerardii, J. greenei, J. gymnocarpus, J. hallii, J. hemiendytus, J. howellii, J. inflexus, J. interior, J. kelloggii, J. leiospermus, J. lesueurii, J. longistylis, J. luciensis, J. macrandrus, J. macrophyllus, J. marginatus, J. maritimus, J. megacephalus, J. mertensianus, J. militaris, J. nevadensis, J. nodatus, J. nodosus, J. occidentalis, J. orthophyllus, J. oxymeris, J. parryi, J. patens, J. pelocarpus, J. pervetus, J. phaeocephalus, J. polycephalus, J. regelii, J. repens, J. roemerianus, J. scirpoides, J. secundus, J. squarrosus, J. stygius, J. subcaudatus, J. subtilis, J. supiniformis, J. tenuis, J. texanus, J. textilis, J. tiehmii, J. torreyi, J. trifidus, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi, J. xiphioides
Subordinate taxa
J. arcticus var. alaskanus, J. arcticus var. balticus, J. arcticus var. mexicanus
Synonyms J. megaspermus, J. triformis var. stylosus
Name authority Willdenow: Sp. Pl. 2: 206. (1799) Engelmann
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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