Flora of North America species comparison

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Juncus arcticus

Juncus xiphioides

arctic rush

iris-leaf rush
Habit Herbs, perennial, 2–10 dm. Herbs, perennial, rhizomatous, 5–9 dm.
Rhizomes

long- creeping.

2–3 mm diam.
Culms

erect, 1–3 mm diam.

erect, 2–6 mm diam.
Cataphylls

several.

0 or 1–2, straw-colored, apex narrowly acute.
Leaves

blade usually absent (present in var. mexicanus).

basal 1–3, cauline 2–6, straw-colored;

auricles absent;

blade 10–40 cm x (3–)7–12 mm.
Inflorescences

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

primary bract barely exceeding to many times longer than inflorescence.

panicles or racemes of 20–50 heads, 2–14 cm, erect or ascending branches;

primary bract erect;

heads 15–70-flowered, obovoid to globose, 7–11 mm diam.
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 green to brown or reddish brown, lanceolate, 2.4–3.7 mm, nearly equal, apex acuminate;

stamens 6;

anthers ½1/2 to equal filament length.
Capsules

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

slightly exserted, chestnut to dark brown, 1-locular, ellipsoid, 2.4–3.8 mm, apex acuminate, not beaked.
Seeds

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

elliptic to obovate, 0.4–0.6 mm, not tailed.
2n

= 40.

Juncus arcticus

Juncus xiphioides
Phenology Fruiting early summer–fall.
Habitat Salt marshes, moist areas, ditches, springs, lake and stream shores
Elevation 500–1600 m (1600–5200 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
AZ; CA; NM; NV; UT; Mexico (Baja California)
[WildflowerSearch map]
[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.)

This species and the next (Juncus ensifolius) are closely related and have been treated as members of a single species (J. xiphioides) by Engelmann. Until a study of the complete subgenus is done, we are hesitant to use a varietal name (J. xiphioides var. triandrus) for the widespread western taxon J. ensifolius.

(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. Ensifolii
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. triformis, J. triglumis, J. trigonocarpus, J. uncialis, J. validus, J. vaseyi
Subordinate taxa
J. arcticus var. alaskanus, J. arcticus var. balticus, J. arcticus var. mexicanus
Synonyms J. xiphioides var. auratus, J. xiphioides var. littoralis
Name authority Willdenow: Sp. Pl. 2: 206. (1799) E. Meyer: Synopsis Juncorum 50. (1822)
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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