Montana Field Guide

PLANTS: A thickened tap-rooted, perennial plant that grows prostrate, 10-20cm tall. The simple to branched caudex surmounts the woody taproot. Sources: Lesica 2019; Lesica et al. 2022

LEAVES: Basal and cauline with an alternate arrangement. Leaf blades are ovate in outline, 1-7 cm long by 1-7 cm wide, glabrous, and covered with a whitish-bloom (glaucous). Petioles 1-11cm long, purplish, and dilated. Petioles have sheaths along the stem that are dry, thin, and transparent (scarious). Leaf blades are pinnately divided (compound) into short-stalked leaflets, 5-25 mm long by 5-20 mm wide. Leaflets are further divided, once or twice, into linear-oblanceolate lobes with a terminal spine (mucronate). Lobes are 1.5-10(12) mm long by 0.5-3.0 mm wide with entire margins and midveins. Sources: Lesica 2019; Lesica et al. 2022

INFLORESCENCE: A compound umbel born on a single peduncle, 4-13 cm long (excludes the leaves). Peduncles are longer than the leaves. Rays of the umbel are 5-15mm long and 13-21 mm or 15-40 mm in diameter when in flower or fruit, respectively. Up to 3 involucral bracts occur at the base an umbel's rays, linear-attenuate in shape, often purplish, 2.5-5 mm long. Rays terminate into an umbellet subtended by 3-7 basally united, linear attenuate, involucel bracts, 1-3.5 mm long with thin hyaline margins. Umbellets have 6-15 yellow or white flowers.
Fruit is of two, 1-seeded mericarps joined on their inner sides (schizocarp). Sources: Lesica 2019; Lesica et al. 2022

Montana has 3 Musineon species in Montana (Lesica et al. 2022). Refer to Lesica (2019) for a botanical key that distinguishes the 6 Musineon species in the western United States.

Big Belt Wild Parsley - Musineon glaucescens, State Endemic
* Stems: Present; grows from a simple or branched caudex.
* Leaves: 2- or 3- times ternate. Glaucous. Ultimate lobes linear-oblanceolate.
* Fruits: At maturity are purplish, at least 5 mm long.
* Distribution: In Lewis & Clark County, Montana.
* Habitat: On limestone talus in the lower subalpine zone of Montana.

Rydberg's Parsley - Musineon vaginatum, PSOC, Regional Endemic
* Stems: Present; grows from a simple or branched caudex.
* Leaves: 2- or 3- times ternate. Not glaucous. Ultimate lobes linear.
* Fruits: At maturity are beige, equal to or less than 4.5 mm long.
* Distribution: In west-central and south-central counties of Montana.
* Habitat: Stony soil, often calcareous, in open Douglas-fir (Pseudotsuga menziesii) forests and woodlands in the valleys to subalpine zones of Montana.

Wild Parsley - Musineon divaricatum
* Stems: Present, usually as a pseudoscape that is often buried.
* Leaves: Once-pinnate. Not glaucous.
* Distribution: In most counties of Montana except those in the northwest.
* Habitat: Stony soil of grasslands, sagebrush steppe, and woodlands in the plains and valley zones of Montana.

TAXONOMY & NOMENCLATURE
Musineon comes from an ancient Greek name for Foeniculum, an umbel-forming genus (Giblin et al. [eds.] 2018). The specific epithet glaucescens refers to the whitish bloom (glaucous) of the leaves (Lesica 2019).

Within the Family Apiaceae, Musineon belongs to the subfamily Apioideae, which is endemic to western North America (Lesica 2019). Morphological traits that define members of this subfamily share similar diagnostics traits found in unrelated or distantly related species, a product of convergent evolution. Morphologically, Musineon glaucescens closely resembles M. vaginatum in having biternate to triternate leaves and similar inflorescence, but differ in fruit size, lobe shape, and presence/absence of glaucous leaves with distributions that don't overlap. Because of the morphological similarities, Lesica placed Musineon glaucescens into the genus Musineon, though he realized this could be a temporary classification (Lesica 2019).

Phylogenetic studies of the subfamily Apioideae demonstrate that morphological and genetic traits might not match well (Lesica 2019). Preliminary analysis of nuclear ribosomal DNA and chloroplast DNA markers, places Musineon glaucescens into the same clade with M. divaricatum and M. vaginatum along with members of Tauschia, Cymopterus, Aletes, and Harbouria genera. Based only on a single sampled specimen, Musineon glaucescens was found to be a sister of Taushia texana and not M. vaginatum. It is possible that the differences in traits between Musineon glaucescens and M. vaginatum reflect habitat, and not genetics (Lesica 2019; see also the Ecology subsection). More research is needed.

Plants grow on shifting to stable limestone talus within the lower subalpine zone (Lesica 2019; Lesica et al. 2022). Slopes are warm and support sparse vegetation (Lesica 2019). Commonly associated species include: Agropyron spicatum, Artemisia michauxiana, Lomatium cous, and Penstemon attenuatus.

Lesica (2019) theorized that the warm, talus slope environment – and not the genetics - in which Musineon glaucescens grows could reflect the differences observed in morphological traits with the similar Musineon vaginatum. Drought stress has been conjectured as an explanation for producing glaucous leaves (Guo et al. 2016). Larger fruits could be a product of a more stressful germination condition (Harper 1977). In contrast, the broader lobes of Musineon glaucescens would often be associated with a more mesic environment.

Plants reproduce by seed.

FLOWERS
Sepals: Obscure with rounded marginal teeth. Petals: 5, separate, dull yellow to white, facing to off-white or pinkish About 1 mm long, obovate in shape with an incurved tip and sometimes a short claw. Stamens: 5, spreading. Anthers, 0.3-0.5mm long. Filaments 0.5-2.0 mm long. Pistil: Singular, inferior, with a 2-chambered ovary (locules). Each chamber terminates into 1 style, 0.7-1.5 mm long, but lacks the swollen base – does not form a stylopodium. The styles diverge from each other.

Flowers of the umbellet can have both stamens and pistil (perfect) or have only stamens (imperfect) in the following arrangements: 1) outer flowers with both stamens and pistil (perfect) and inner flowers of only stamens, 2) all flowers with only stamens, or 3) all flowers with both stamens and pistil

FRUITS
Schizocarp: Two, 1-seeded mericarps joined on their inner sides. Narrowly ellipsoid, and partially roundish, 4-7 mm long by 1.5-4 mm wide. 1-9 shizocarps per umbellet. Mericarp: 5-7 mm long, glabrous or roughened (scaberulous). Ribs mostly prominent. Between ribs are 1-4 oil tubes.

Threats to the populations and habitat of Musineon glaucescens are not known.