Thlaspi montanum L. var. montanum

  • Authority

    Holmgren, Patricia K. 1971. A biosystematic study of North America Thlaspi montanum and its allies. Mem. New York Bot. Gard. 21: 1-106.

  • Family

    Brassicaceae

  • Scientific Name

    Thlaspi montanum L. var. montanum

  • Description

    Species Description - Glabrous, mostly glaucous perennials with a simple to branched (mostly) caudex; stems 1-many, slender, up to 40 cm tall (including the mature infructescence), rarely branched, (0.5-)4-15(-32) (averaging 9.5) cm tall below the infructescence, greenish, straw-colored, or purplish; basal leaves numerous, greenish to purplish, oval to oblong, mostly with an entire (but sometimes denticulate to dentate) margin, (9-)13-34(-70) (averaging 23) mm long, (2-)4-9(-15) (averaging 6) mm wide, the blade (5-)6-18(-25) (averaging 11.4) mm with a (4-)5-20(-50) (averaging 13.5) mm petiole, the petiole 0.8-1.1 (-2) times as long as the blade; cauhne leaves (3-)4-9 (-19), sessile (seldom short-petiolate on the lower cauline leaves) and auriculateclasping, greenish or purplish, with a very narrow entire to dentate usually hyaline margin and an obtuse to acute apex, from overlapping to scarcely half as long as the internode, (4-)7-18(-28) (averaging 11.9) mm long, (l-)3-8(-16) (averaging 5.4) mm wide; petals (3.4-)4.2-7(-8.5) (averaging 5.5) mm long, white to pinkish-purple, spatulate, (1.1-) 1.5-2.7(-4.2) (averaging 2.1) mm wide; sepals greenish to purplish with a narrow hyaline border, (1.6-)1.9-3(-4) (averaging 2.5) mm long; longer stamens up to 4.5 mm long, the shorter ones up to 3.5 mm long; anthers yellow (very rarely purple); infructescence (0.5-)2-8(-25) (averaging 4.9) cm long, (1-)2-3.5(-5.2) cm wide, mostly not compact, i.e., (1-)2-17(-40) (averaging 8-9) pedicels in lower 2 cm of infructescence; pedicels mostly horizontal to horizontalascending, the lower ones up to 15 mm long, becoming shorter upwards; silicles mostly horizontal to horizontal-ascending, obovate to obcordate, from obtuse to truncate or emarginate at the apex, winged or non-winged, greenish to purplish, (2.5-)5-8(-12) (averaging 6.4) mm long, (1.5-)2.6-4.5(-6.6) (averaging 3.5) mm wide; seeds 4-8 per silicle, dark brown, hghtly striate, some with a prominent raphe, 1.1-2.1 mm long; style (0.4-)l.1-2.2(-3.2) (averaging 1.6) mm long. Flowering time: April-August. Chromosome number: n = 7, 14.

  • Discussion

    T. cochleariforme de Candolle, Reg. Veg. Syst. Nat. 2: 381. 1821. ("Hab. in Sibiria et Dahuria ad jugum Yablonoi-Chrebet.")

    T. cochleariforme sensu Nuttall, Jour. Acad. Phila. 7: 13. 1834, not DC. 1821. T. nuttallii Rydberg, Bull. Torrey Club 29: 235. 1902. (On the borders of a creek on Flat-Head river.)

    T. alpestre var glaucum A. Nelson, First Rep. Fl. Wyo. 84. 1896. T. glaucum (A. Nelson) A. Nelson, Bull. Torrey Club 25: 275. 1898. T. fendleri var glaucum (A. Nelson) C. L. Hitchc, Vase. PI. Pac. N. W. 2: 554. 1964. (.4. Nelson 1777, LaPlata Mines, Wyo., 21 Aug 1895, holotype, R M !; isotypes, GH!, MO!, NY!, UC !, US!).

    T. coloradense Rydberg, Bull. Torrey Club 28: 280. 1901. T. fendleri var coloradense (Rydberg) Maguire, Am. Midi. Nat. 27: 469. 1942. {E. A. Bessey s. n.. Bald Mt. west slope, alt 11,500 ft, near Pike's Peak, 1 Aug 1896, holotype, NY!).

    T. purpurascens Rydberg, BuU. Torrey Club 28: 281. 1901. T. alpestre var purpurascens (Rydberg) Ostenfeld, Skr. Vidensk.-Selsk. Christiania (1909) 8: 47. 1910. Intermediate to var fendleri. {E. Palmer 571, near Prescott, Arizona, in 1876, holotype, NY!; isotypes, MO!, NY!).

    T. glaucum var pediinctdatum Payson, Univ. Wyo. Publ. Bot. 1: 152. 1926. (L. F. Henderson 2893, near Kendrick, Idaho, 21 Apr 1894, holotype, RM!).

    T. glaucum var hesperium Payson, Univ. Wyo. Publ. Bot. 1: 154. 1926. T. hesperium (Payson) G. N. Jones, Univ. Wash. Publ. Biol. 5: 161. 1936. T. fendleri var hesperium (Payson) C. L. Hitchc, Vase. PI. Pac. N. W. 2: 554. 1964. (H. M. Hall 8570, Dorleska, in the Salmon Mts. of Trinity Co., Cahfornia, 18 Jul 1909, holotype, RM!; isotypes, C(2)'.. GH!, MO!, NY!, S!, UC!, US!).

    T. fendleri var tenuipes Maguire, Am. Midi. Nat. 27: 469. 1942. {Maguire 19998, West slopes, Mayfield Canyon, 1/2 mi above Ranger Station, 10,928 ft, frequent, loose talus, SanPete Co., Utah, 8 Aug 1940, holotype, UTC!).

    T. australe A. Nelson, Am. Jour. Bot. 32: 287. 1945. (A. & R. Nelson 1545, west side Baboquivari Peak, Arizona, 16 Apr 1935, holotype, RM!; isotypes, GH!, MO!, NY!, S!, UC!, US!). Intermediate to var fendleri.

    This variety is a very polymorphic complex in which geographical correlation of morphological expressions desirable for taxonomic recognition is lacking. Several patterns of variation in the U. S. partially correlate with latitude and will be discussed in the following paragraphs.

    a) Length of floral parts.

    Positive correlation exists between the lengths of petals, sepals, and style. Mapping of style lengths (Fig. 10) shows a trend from very long (greater than 2.5 mm) in New Mexico and Arizona (var fendleri) to short ones (0.3-0.5 mm) in Wyoming, Idaho, and southwestern Montana (T. parviflorum). The vast majority of plants have styles measuring 1-2 mm.

    b) Compactness of infructescence.

    The infructescences tend to be more compact in the southern part of the United States (Fig. 60), as determined by the number of pedicels in the lower 2 cm of the mature infructescence, racemes with 10 or more arbitrarily being considered compact. Though a compact infructescence is characteristic of the majority of plants in Arizona, New Mexico, and southern Utah, it is also found in very scattered specimens from throughout the range in the U. S. in the alpine and subalpine habitats, such plants usually having a shorter stature and a compact fruiting raceme.

    c) Length of stem.

    Although Payson (1926) doubted that T. fendleri (southern Wyoming, Colorado, New Mexico, Utah, and Arizona) could be maintained as distinct from T. glaucum (Montana, Wyoming, Colorado, New Mexico, Utah, and Arizona), he separated them on the basis that the former had shorter (rarely over 1 d m long) stems up to the inflorescence. The alleged difference is unreal, as the length of the stem is perhaps one of the most variable features of Thlaspi, undoubtedly being affected by the environment. It is not at all uncommon to see plants ranging from very tall to very short within one collection (Kern 788, Fig. 61).

    d) Branching of the caudex.

    The southern plants mostly have an unbranched (or 1-branched) caudex, and thus no basal rosettes of leaves without flowering stems, while the northern plants are mostly caespitose. Since collectors often divide multicipital plants into their constituent flowering stems, many such fragments appear on herbarium sheets to have been plants with a single rosette.

    e) Length of peduncle.

    Still another such trend is for the peduncles to vary from very short (or lacking) in the plants from the south to exceptionally long (var pedunculatum) in those from Idaho and eastern Washington and Oregon. The use of peduncle length as a taxonomic character will be discussed below.

    Of these various trends, only a combination appears to be taxonomically significant and useful in delimitation of infraspecific taxa. It will be discussed under var fendleri.

    Nelson (1896) described this taxon as a variety (var glaucum) of T. alpestre. Two years later, he elevated it to specific rank stating that it differs from T. alpestre in its uniformly larger size, many stems, numerous and larger cauline leaves, longer pedicels, and longer fruiting raceme.

    Payson (1926) named a long-peduncled (5-10 cm) phase from western Montana, northern Idaho, eastern Washington, and Oregon as T. glaucum var pedunculatum. This feature was found to be a variable character within populations. Figure 62 shows two plants from Mt. Colonel Bob, Washington, one of which has long peduncles suggestive of var pedunculatum while the other does not. In the entire mass collection from that area (Kern 763), 23 plants had peduncles that were longer, and 40 that were shorter, than 5 cm. Other collections from Mt. Colonel Bob (Thompson 7294, GH, MO, UC, WTU; Thompson 9401, GH, MO, NY, UC, US, WTU; Thompson 9975, MO, NY, WTU) provide a ratio of 17 long-peduncled plants to 22 short ones.

    Specimens such as the following have unusually long peduncles: Christ 10950, 7 mi N of Calder, Shoshone Co., Idaho (NY); Leiberg 1361, near Wiessner's Peak, Idaho (GH, MO, NY, US); M. & R. Ownbey 2024, 2 mi SE of Fernwood, Benewah Co., Idaho (COLO, DAO, GH, MO, NY, S-2, UC, US, UTC, WTU); McCalla 5605, Blue Mts., Union Co., Oregon (WTU).

    Fields Spring State Park, Asotin County, Washington, was the site of another mass collection (Kern 788, Fig. 61), which was also mixed as to long-peduncled (29 plants) and short-peduncled (12 plants) forms. Cronquist (5801, COLO, DAO, GH, NY, S, UC, US, UTC, WTU) made a large collection at this area which has been seen to include 8 long- and 25 short-peduncled plants.

    There is an area in northern Idaho (Kootenai, Benewah, Latah, and Clearwater counties) from which almost all collected plants seen have long peduncles, but elsewhere (Montana, Washington, and Oregon) this alleged varietal distinction is not obvious. For example, from fifty herbarium collections (many with several duplicates), twenty-three, from scattered localities in Washington, had a mixture of longand short-peduncled forms.

    Whether the variation is due entirely to effects of the environment, to purely genetic factors, or to a combination of both, is not known. Henderson has written on the label of the type specimen of var pedunculatum Payson (Henderson 2893, grassy field, near Kendrick, Idaho, RM) that this is a pecuhar form, because of habitat, height of stem, and less enduring root. Four of m y collections (Kern 763, Mt. Colonel Bob, Washington; Kern 788, Fields Spring State Park, Asotin Co., Washington; Kern 789, W of Anatone, Asotin Co., Washington; Kern 846, High Divide Trail, Olympic National Park, Washington) were growing with more abundant and taller vegetation than is common for Thlaspi and all were a mixture of long- and short-peduncled plants. Those from Asotin County (Kern 788, Fig. 61) were mostly growing in the shade of shrubs and were the most robust. Since length of the peduncle is at least partially affected by the environment and since long-peduncled plants occur (in mixture with short-peduncled ones) at scattered localities, its use as a diagnostic taxonomic character is not believed to be justified.

    Variety hesperium Payson, a phase with reduced cauline leaves scarcely half as long as the internodes, presents the same array of variability as var pedunculatum. i.e., numerous mixed populations. As in var pedunculatum, there are herbarium sheets representative of var hesperium as Payson described it. A few examples are: Hitchcock 7944, 12 mi NE of Salmon La Sac, Kittitas Co., Washington (GH, RM, UC, WTU); Thompson 6397, along Beverly Creek Trail, Kittitas Co., Washington (GH, MO, US, WTU); Thompson 12382, serpentine slopes of Red Mt., Siskiyou Mts., Jackson Co., Oregon (MO, NY, UC, WTU-2); Copeland 3905, Mt. Eddy, Siskiyou Co., Cahfornia (GH, MO, NY); Alexander & Kellogg 5789, Union Creek, NW of Trinity Center, Trinity Co., California (UC, US).

    As suggested by the cited specimens, this phase is most prevalent in the Wenatchee Mts., Washington, Jackson Co., Oregon, and northern California. Jones (1936) went so far as to combine all the northwestern plants into one species, T. hesperium, separating them from T. glaucum (of the Rocky Mts.) on the basis of mostly ascending pedicels, smaller flowers (4-6 mm long), narrower petals (2-2.5 mm wide above the middle), cauline leaves normally shorter than the internodes, and mostly non-glaucous leaves. This is an unrealistic separation that breaks down for each character. For example, the petal length ranges from 3.5-8.0 m m for plants of the Northwest versus 3.7-8.5 m m for Rocky Mountain plants. Furthermore, certain specimens from the Olympic Mountains (St. John 5764, WTU) closely match the isotype of T. glaucum (GH) from Wyoming.

    Almost all of m y mass collections from the Northwest have shown the length of the cauline leaves to be a variable character within populations. Three collections (Kern 826, 827, 828) from the same locality in Tumwater Canyon, Chelan Co., Washington yielded 84 plants with cauline leaves reduced (less than half the length of the internode), 29 with ample cauhne leaves, and 65 with a mixture of the two on the same plant. Another mass collection from Strawberry Mt., Oregon (Kern 787) showed 18 plants with reduced cauline leaves, 16 with ample leaves, and 11 wdth a mixture. Figures 61, 62, 63 show plants with both short and long cauline leaves from three localities (Kern 763, Mt. Colonel Bob, Washington; Kern 788, Asotin Co., Washington; and Kern 833, Mt. Rainier National Park, Washington).

    Examples of herbarium specimens with variable length of cauline leaves are as follows: Thompson 14581, Cleman Mt., Kittitas Co., Washington (COLO, GH, MO, NY-2, S, UC, US, WTU); Rydberg & Bessey 4144, Bridger Mts., Montana (NY, US); Cronquist 5801, Fields Spring State Park, Asotin Co., Washington (COLO, DAO, GH, NY, S, UC, US, UTC, WTU); Spellenberg 1502, 12 mi N of Salmon La Sac, Kittitas Co., Washington (COLO, DAO, GH, NY, RM, UC, UTC, WTU).

    Frequently the main two or three stems have ample cauline leaves while three or four secondary stems have very much reduced cauline leaves (McCalla 5605, Blue Mts., Union Co., Oregon, WTU).

    Thlaspi montanum is normally yellow-anthered, but purple-anthered plants infrequently occur in New Mexico, Nevada, Utah, and Colorado, and might be expected to occur in Arizona. Examples are: .A. Holmgren 1434, Liberty Pass, Ruby Mts., Elko Co., Nevada (UTC); N. Holmgren 242, middle fork of Manti Canyon, Wasatch Plateau, SanPete Co., Utah (NY, UTC); Bethel & Clokey 3985, Mt. Morrison, Jefferson Co., Colorado (C-2, COLO, F, GH, MO, RM, S, UC-2, US, UTC); Arsene & Benedict 15549, vic. of Santa Fe, Lake Peak, New Mexico (F, US). Many of these collections have a mixture of dark purple, light purple, and yellow anthers on the same herbarium sheet.

    At higher altitudes, especially in Colorado, there exist low-growing, caespitose plants with compact, short infructescences which Rydberg (1901) named T. coloradense.

    It cannot be denied that such extreme dwarfed plants superficially seem distinct enough, as exemplified by these specimens: Payson 1566, Pike's Peak, above timberhne, Colorado (MO, RM); Osterhout 4363, Gray's Peak, Clear Creek Co., Colorado (RM); Clements & Clements 427, summit Pike's Peak, Colorado (C-2, GH, MO-2, NY, RM-2, US).

    This phase has been collected numerous times in the vicinity of Pike's Peak, where there probably is continuous clinal variation in stem length from 2 to over 15 cm tall (including the mature infructescence). A few taller specimens are cited below: G. C. Broadhead s. n., below snowline. Pike's Peak (MO); G. C. Broadhead s. n., at snowline. Pike's Peak (MO); Mrs. S. B. Walker s. n., Pike's Peak region, at 12,000 ft (COLO); E. B. Payson 1585, subalpine basin. Pike's Peak (COLO, MO, RM).

    One specimen collected on the summit of Pike's Peak (H. L. Zobel s. n., MO) has a mixture of very short (4 cm in flower) and taller (10 cm in flower) plants. Maguire (1942) reduced T. coloradense to varietal status under T. fendleri, pointing out that it could not be maintained at the specific level on the basis of its alleged caespitose habit, an inconstant condition and not unknown in T. fendleri.

    Attempts to delimit the high-altitude plants from those of lower elevations or to correlate the dwarfed habit with altitude were not successful. Plants with stems less than 10 cm long may appear in collections at relatively low elevations whereas plants with stems over 10 cm long have been collected at high elevations in Colorado. For example: C. S. Crandall s. n., Front Range, 12,000 ft (MO); M. L. Hunken s. n., Niwot Ridge, Science Lodge, 11,000 ft (COLO, NY, WTU); W. A. Weber 5820, trail to Lakes of the Clouds, Sangre de Cristo Range, 11,000 ft (COLO); J. Michener 414, San Juan National Forest, 18 mi SE of Silverton, 10,800 ft (COLO, DAO, MSC). In Rocky Mountain National Park dwarfed (C. H . Knowlton s. n., wet mt. slope. Fall River Pass, 12,000 ft, G H ) and non-dwarfed plants (Willard 6020, SW of Fall River Pass, Trail Ridge, between 11,500 and 12,465 ft, Colorado, COLO) occur in relatively close proximity.

    Maguire (1942) described from Utah a loosely multicipital ecological variant, var tenuipes, which was growing on loose, mostly calcareous talus. This phase was recollected in Utah (N. Holmgren & P. Kern 3745). In our collection, stems were few to single on the flat open wind swept area of the Wasatch Plateau. A few yards away on active talus, many plants with very loose branching of the caudex occur. Many plants, scattered sporadically around the range, develop the same loose branching of the caudex, and the variant is not recognized taxonomically in this treatment.

    Very robust specimens of var montanum have been collected by Constance & Rollins (2877, GH, MO, NY, RM, UC, US, UTC, WTU; 2887, GH, MO, NY, RM, S, UC, US, UTC, WTU) on serpentine in Humboldt Co., California, at 400 feet elevation. Except for the long peduncle and non-congested infructescence, these specimens would probably key to var fendleri.

    Plants of var montanum with style length under 1.0 m m are rare, but two such are: Bamberg 407, Flattop Mt., Silverbow Co., Montana (COLO); Hitchcock & Muhlick 14855, Anaconda Mts., Deerlodge Co., Montana (WTU). These plants do not match T. parviflorum in any respect other than style length which is still longer (0.5-0.8 mm) than would be expected for T. parviflorum.

    The crossability of this variety (Figs. 50, 51, 52) is as variable intravarietally as intervarietally (Table V). Pollen stainability was almost always over 70% with the exception of low stainability for the crosses between diploids and tetraploids.

  • Distribution

    Distribution (Fig. 59). Growing on moist or dry, open, rocky, scree, or talus slopes, alluvial fans or flats, limestone cliffs, moist to dry subalpine to alpine meadows, where often near snowbanks, forest clearings, and streamsides in North America and Eurasia; in N. Am., occurring in northwestern Wash., southwestern Oreg., northern Calif., east through central Wash, and Oreg. and Ida. to southwestern Mont., south throughout the Rocky Mts. in Wyo., Colo., and Utah, to Ariz., N. M., Nev., western

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