Little yellow rattle – Rhinanthus minor

Little yellow rattle

Rhinanthus minor

Since Rhinanthus minor and possibly both its subspecies (see numerous notes below) may appear in Alaska (subtaxa included in numerous floras and databases), and they can be difficult to nearly impossible distinguish by morphology alone, I am providing information on the parent species and both subspecies in this article. I believe that the Arctic rattlebox (Rhinanthus minor ssp. groenlandicus) is photographed here primarily due to the dentate margins on the leaves (although it can be present in both subspecies) and the whitish tip of the corolla. This may be the dominant (or only) subspecies in Alaska.

Subspecies

Rhinanthus minor ssp. groenlandicus (Arctic rattlebox)
Rhinanthus minor ssp. minor (cockscomb rhinanthus, little yellow rattle, petit rhinanthe)

Common Names

Parent Species:
little yellow-rattle
Little yellow rattle
Rattlebox
Subspecies Common Names:
Arctic rattlebox
petite rhinanthe

Synonyms

none for parent species (ITIS)
Synonyms for Subspecies
Synonyms of Rhinanthus minor ssp. groenlandicus:
Rhinanthus arcticus
Rhinanthus borealis
Rhinanthus groenlandicus
Rhinanthus minor ssp. borealis
Synonyms of Rhinanthus minor ssp. minor:
Rhinanthus crista-galli
Rhinanthus rigidus
Rhinanthus stenophyllus
Rhinanthus crista-galli var. Fallax
Rhinanthus kyrollae
Rhinanthus borealis ssp. kyrollae

Genus: Rhinanthus (yellow rattle, rattleweed)
Family: Orobanchaceae (broomrape)
Order: Lamiales
full classification

Duration – Growth Habit

Annual – forb/herb (hemiparasitic)

Note on Taxonomy and Distribution

Rhinanthus, a genus of hemiparasitic plants, presents unique challenges for taxonomists and ecologists, particularly in regions like Alaska. Some species were introduced from Europe to North America, and since then, accurately tracking their spread has been difficult. This is due in part to the plant’s potential for rapid proliferation and the lack of comprehensive surveillance. Complicating matters further is the considerable morphological variability within Rhinanthus, largely influenced by its hemiparasitic nature and adaptability to various hosts and environments. This variability often hinders clear identification and classification based solely on morphological traits, creating confusion in distinguishing among the various entities within the genus.

This uncertainty is reflected in the conflicting information found in floras and databases such as GBIF, Flora of North America, NatureServe Explorer, Flora of British Columbia, etc. Discrepancies arise due to different methodologies, regional variations, and evolving taxonomic understanding. Rhinanthus‘ taxonomy itself is fraught with contention, with numerous synonyms in use and ongoing debates over the correct classification of entities within the genus. These complexities underscore the need for further research, including genetic studies and extensive fieldwork, to clarify the relationships among Rhinanthus entities and accurately map their distribution. The resulting clarity would not only contribute to our understanding of this genus but also inform effective conservation and management strategies, particularly given Rhinanthus’ potential impact on native ecosystems in Alaska.

The information presented here is the best that I could find from numerous sources as of May 2023. It is possible that some information may be erroneous and will likely be updated in the future.

Identification and Information

Rhinanthus minor displays hemiparasitic behavior, forming connections with the root systems of nearby plants and extracting nutrients from them. This ability allows it to thrive in various habitats and conditions and significantly influences the plant’s morphology. The characteristics of the host plant can cause variations in the size, shape, and overall development of Rhinanthus minor, thus greatly increasing the difficulty of identifying subspecies. This plant is known to parasitize a diverse array of species, at least 50 from 18 different families, including 16 species from the Poaceae (true grasses) and 11 species from the Fabaceae (legume family).

For instance, when R. minor parasitizes a legume species such as Vicia cracca, it tends to grow significantly larger, with taller stems, more branches and leaves, a higher total leaf and branch area, a higher number of buds and seed capsules, and a higher leaf, reproductive, and total dry weight than when it parasitizes a grass species like Festuca rubra. This variation suggests that the quality of the host plant can directly affect the morphology of R. minor, making some species better hosts than others.

Description

Rhinanthus minor, commonly known as the Little Yellow Rattle, is an annual herb from the Orobanchaceae family. This plant derives its common name from the distinctive rattle-like sound its mature seeds make when shaken in their capsules. The root system of this plant is shallow and fibrous, with the capacity to form connections with the root systems of nearby plants for nutrient acquisition. The plant features erect, somewhat 4-angled stems that are simple or slightly branched, ranging from 10-80 cm tall. These stems can sometimes bear black streaks and are nearly smooth to thinly soft-hairy at the nodes and in lines down opposite 2 of the 4 sides. The leaves of this species are opposite, unstalked, and range from lanceolate to oblong, with a length of 1-5 cm. They are prominently toothed and have rough, appressed hairs.

The inflorescence of Rhinanthus minor is a leafy-bracted, terminal, spike-like cluster of several to many nearly unstalked flowers. The flowers have yellow, tubular corollas that are 10-15 mm long and 2-lipped. The calyces are membranous and 4-toothed, becoming much inflated in fruit, resembling a flattened net-veined balloon. The plant’s seeds are contained within nearly globe-shaped, flattened capsules that are 8-15 mm long and enveloped by the calyx balloon. When the capsules mature, they turn brown and dry, encapsulating the seeds that rattle upon shaking, hence the common name “Little Yellow Rattle”.

There are two subspecies of Rhinanthus minor found in North America:

1. Rhinanthus minor ssp. groenlandicus: This subspecies has leaves that are oblong with coarsely dentate margins. The teeth of the galea of the corolla are whitish. The stems are hairy on 2 opposite sides. It is found in Greenland, the northern parts of North America, and in Europe. The typical habitat for this subspecies includes moist meadows, river valleys, and seashores. Its elevation ranges from 0-1100(–2700) m.
2. Rhinanthus minor ssp. minor: This subspecies has ovate-oblong to linear-lanceolate leaves with crenate-serrate margins (distal leaves sometimes dentate). The teeth of the galea of the corolla are bluish or bluish-gray. The stems are glabrous. It is found in Greenland, St. Pierre, and Miquelon, various provinces in Canada, several states in the United States, and in Europe. Its typical habitat includes clearings, meadows, rocky slopes, open, grassy slopes at edges of mixed woods, and roadsides, often on calcareous soils or rocks. Its elevation ranges from 0–600(–2700) m.

Note: Both subspecies are quite similar, and differentiation can be challenging. Bear in mind that these descriptions provide the most common characteristics for each, but some variation may occur within populations due to the plant’s hemiparasitic nature and the influence of its host plant.

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Uses

For information only (typically historical) – I take no responsibility for adverse effects from the use of any plant.

The primary significance of Rhinanthus lies in its ecological role and potential use in agricultural contexts. As a hemiparasitic plant, Rhinanthus can draw nutrients from other plants, impacting the composition of plant communities. This has made it a subject of interest for ecological restoration and management. Rhinanthus has been studied in agriculture for its potential use as a cover crop, given its ability to suppress more aggressive grass species and allow for a more diverse range of species in meadows and pastures. This could contribute to improved soil quality and ecosystem health.

Furthermore, R. minor plays a key role in biodiversity conservation and grassland restoration projects. By parasitizing and decreasing the size of dominant species in an ecosystem, it helps create gaps that can be colonized by other species that previously couldn’t establish themselves. This dynamic helps reduce competition and facilitates an increase in biodiversity.

Rhinanthus also has potential in scientific research, particularly in studying plant-plant interactions, coevolution, and parasitism. Its complex relationships with host plants make it an interesting model system for ecological and evolutionary studies.

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Distribution and Habitat

Map includes distribution information from parent species and both subspecies from NatureServe Explorer and GBIF (links to individual sources in Reference section below).

Rhinanthus species inhabit a broad geographical range, extending from Europe to North America, including regions like Alaska. Known to thrive in various habitats, these plants are predominantly found in grasslands, meadows, and fields. Some species were introduced from Europe to North America, and the extent of their proliferation remains an ongoing area of study due to the plant’s rapid adaptability and spreading capability.

In the context of Alaska, Rhinanthus species are found across various habitats, including grasslands and wet meadows. The region’s climate and environmental conditions allow these hemiparasitic plants to establish and thrive, especially in areas with abundant preferred host plants. This, in turn, has potential implications for local ecosystems, given Rhinanthus’ ability to impact host plant communities.

Although this genus is widely distributed, its exact range and the distinct territories of specific species or entities within the Rhinanthus genus remain subjects of study. The morphological variability of Rhinanthus, combined with its propensity to adapt to various hosts, leads to difficulties in accurately mapping its distribution. It’s also important to note that human activities, including agriculture and changes in land use may influence Rhinanthus’ distribution.

Classification

References and Further Reading

Guidebook

Field Guide to Alaskan Wildflowers, Pratt, Verna E. pg. 31

Classification and Taxonomy

ITIS Database:
Rhinanthus minor L. Taxonomic Serial No.: 504749
Rhinanthus minor ssp. groenlandicus (Chabert) Neuman Taxonomic Serial No.: 524617
Rhinanthus minor ssp. minor L. Taxonomic Serial No.: 524618

Uses

See articles in Description and Information

Map and Distribution

GBIF Database:
Rhinanthus minor L.
Rhinanthus minor subsp. minor Linnaeus

NatureServe Explorer:
Rhinanthus minor
Rhinanthus minor ssp. groenlandicus
Rhinanthus minor ssp. minor

Description and Information

Rhinanthus minor population genetic structure and subspecies: Potential seed sources of a keystone species in grassland restoration projects, Kelly Houston and Kirsten Wolff, Perepectives in Plant Ecology, Evolution and Systematics, Volume 14, Issue 6, December 20, 2012, pages 423-433

Westbury, Duncan B. “Rhinanthus Minor L.” Journal of Ecology, vol. 92, no. 5, 2004, pp. 906–27. JSTOR, http://www.jstor.org/stable/3599388. Accessed 12 May 2023.

Rhinanthus minor ssp. groenlandicus, USDA

Flora of British Columbia:
Rhinanthus minor L.
Rhinanthus minor subsp. groenlandicus L.
Rhinanthus minor L. subsp. minor

Flora of North America:
Rhinanthus minor Linnaeus Amoen. Acad. 3: 54. 1756.
Rhinanthus minor subsp. groenlandicus (Chabert) Neuman Bot. Not. 1905: 257. 1905.
Rhinanthus minor subsp. minor