Juncus bryoides F.J.Herm.

Authority

Ertter, Barbara J. 1986. The Juncus triformis complex. Mem. New York Bot. Gard. 39: 1-90.

Family

Juncaceae

Scientific Name

Juncus bryoides F.J.Herm.

Description

Species Description - Plants 0.3-2(-2.5) cm tall, turning reddish, drying pale reddish or brown; leaves to 0.9 cm long, ¼-1 times the height of the plant; culms to ca. 150, 0.1-1.8(-2.2) cm long, 0.1-0.2 mm thick; bracts (l-)2, ovate (lanceolate), ± acute, usually unpigmented, sometimes brownish at base, 0.3-0.9 mm long, subequal; pedicels to 0.2 mm long; flowers one, mainly trimerous; tepals (4-)6(-8), lanceolate to acutely oblong, (1-) 1.2-2.3(-2.8) mm long, 0.4-0.6 mm wide, subequal or the inner to 0.2 mm longer, acute to acuminate, incurved over the capsule, the central band narrowly tapering, not reaching the apex, 0.05-0.2 mm wide, lustrous, usually turning dark red or brown to almost black with the base sometimes remaining olive-green, not sharply differentiated from the membranous margins, these 0.150.25 mm wide, the inner edges concolorous with the center, otherwise unpigmented (the whole often giving a striped aspect to the mature flower); stamens (2-)3(-4), 0.5-0.9 mm long, ca. ½ the length of the tepals; filaments 0.3-0.6 mmlong; anthers 0.15-0.25 mm long, ca. 1/3-½ the length of the filaments; style lacking or at most 0.1 mm long; stigmas (2-)3, 0.2-0.3 mm long, included at anthesis; capsule ovoid to ellipsoid, (2-)3-valved, terete, rounded, shorter than the tepals by 0.1-0.7 mm, usually concealed by the tepals, (0.7-)1.0-1.9 mm long, 0.5-1.0 mm wide, pale reddish; seeds to eight per row and ca. 40 per capsule, ovoid to globose, somewhat apiculate or umbonulate, 0.3-0.5 mm long (larger extreme in the Sierra Nevada), smooth or faintly transversely lined at 30 x (Fig. 5d-f); 2n = ca. 38.

Discussion

Type. UNITED STATES. California. San Bernardino Co.: Bear Valley, San Bernardino Mts., very abundant on wet sandy flats, ca. 6000 ft, 3-16 Jun 1886, Parish 1859 (Holotype: US!; Isotypes: DS!, F!, GH!, JEPS!, MICH!, MO!, NY!). Often growing with J. tiehmii, also with both varieties of J. hemiendytus and J. capillaris, rarely with J. luciensis, J. kelloggii, or J. uncialis. From its original discovery as a component of Bolander’s Tuolumne River collection in 1866 to its description by Hermann 82 years later, J. bryoides was included within either J. uncialis or J. triformis var. unifloras. For example, the type collection from Bear Valley (now largely inundated by Bear Lake) had been cited by Parish (1910) as one of the southernmost stations of J. triformis var. uniflorus. Juncus bryoides is probably the easiest species in the J. triformis complex to recognize on sight. Recognition, however, is largely a matter of gestalt, so the distinctiveness of this species is difficult to communicate in descriptions and keys. “Looks like J. bryoides” versus “Does not look like J. bryoides” is unfortunately not acceptable as a key break. The most diagnostic feature is the inward curvature of the tepals over the ovoid capsule, described by Hermann as “tulip-like in appearance.” Because of this distinctiveness it is difficult to place the species within the complex. The exclusively solitary flowers and smooth seeds would associate J. bryoides with the “uncialis” group, but the preferred substrate and the color and shape of the tepals and bracts are more reminiscent of the “kelloggii” group. The species lacks both the ridged seeds of J. triformis and the reduced chromosome number of J. leiospermus, which means that the “bryoides” line is unlikely to have arisen from either of these two extant species. Instead the seeds have the narrowly transverse honeycomb pattern that I believe comes closest to the primitive condition, while the chromosome number (2n = 38) is the closest in the complex to that known for the perennial members of subgenus Graminifolii. Probably J. bryoides is best interpreted as the lone highly derived end-product of a separate third line, in which the intermediate species illustrating the stepwise reduction series from the long-styled, many-flowered ancestral complex have been lost. If J. bryoides does represent an isolated lineage that diverged from the rest of the complex at an early stage, the question of the fate of the intermediates then arises. It is likely that the same adaptive features that made J. bryoides so successful over such a wide environmental range allowed it to displace any ancestors. Under optimum conditions J. bryoides can form dense enough stands to color the ground red, and could thereby conceivably have crowded out any less successful relatives. Furthermore, if inadequate reproductive barriers had developed, the well-adapted J. bryoides genes could have simply swamped those of any less successful relative by introgression. As a further peculiarity, smut-infected plants occur in certain populations of J. bryoides. The smut infecting the culms and leaf-bases of a few plants in Howell 25452 (=Munz 14054 p.p.) from Inyo County has been identified as Urocystis junci Lagerh. (det. by R. Duran, 1984). A few plants in Enter & Strachan 3693 from Mono County and Tiehm 6084 from Elko County, Nevada, are affected with a similar smut. Although all three collections represent mixed populations with J. tiehmii, no infected plants of the latter species have been found. This may be taken as further evidence that J. bryoides is phylogenetically isolated from the rest of the complex. Alternatively, morphology may be the critical factor, as the smut was also found on one plant of J. hemiendytus var. abjectus: True & Howell 7719 (CAS) from Nevada County. Both J. bryoides and J. hemiendytus have relatively broad leaves and a compact habit that may provide the necessary microenvironment for smut infection, in contrast to the narrower leaves and comparatively looser habit of J. tiehmii. Within the J. triformis complex, J. bryoides has the greatest geographic and altitudinal range as well as the broadest ecological limits. Its geographic range is similar to that of J. tiehmii but extends farther to the east. I suspect that this easily overlooked plant will prove to be more generally distributed in the northern and eastern parts of its range, especially in Utah, than present collections indicate. It most frequently grows in fine sandy soils, often with J. tiehmii, but also grows in more clayey soils with J. hemiendytus. In these mixed populations it is often in the slightly drier microhabitats, for example on higher ground or away from the protection of other plants. In light of the relatively broad geographic and ecological limits, one might expect to find some infraspecific subdivisions. There is a certain amount of morphological variation, specifically in the coloration and size of plants and floral parts, but this variation apparently reflects vigor and maturity and has little or no genetic basis. Hermann regretted not being able to use the earlier name J. saginoides, which he considered “very appropriate” for this species. Actually, I find his chosen epithet more descriptive of these moss-like plants. An illustration of J. bryoides appears in Hermann’s 1975 treatment of the Rocky Mountain rushes. I am aware of no vernacular names and would therefore suggest mosslike dwarf rush.

Distribution

Widespread, growing in a diversity of habitats such as washes, swales in meadows, and edges of seepage areas on rock outcrops, most frequently on fine sandy soils, occasionally on more clayey soils, sometimes in such abundance as to tinge the ground red, from extreme western Colorado and central Idaho to the mountains of the northern Great Basin in Nevada and Oregon, south through the Wasatch Range to central and southwestern Utah, and through the Sierra Nevada to the Sierra San Pedro Mártir of

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