Pincushion plant – Diapensia obovata

Alaska Wildflowers | White

Pincushion plant

Diapensia obovata

*There is not yet agreement on this taxon. ITIS and most US sources now list D. obovata as a distinct species from D. lapponica. This is discussed further in the sections below.

Common Names

pincushion plant
Alaskan pincushion plant
Lapland diapensia

Synonyms

Diapensia lapponica var. obovata
Diapensia lapponica var. rosea

Subspecies

none

Genus: Diapensia
Family: Diapensiaceae
Order: Ericales
full classification

Duration – Growth Habit

Perennial – Subshrub

Identification and Information

Diapensia obovata, also known as the pincushion plant or Alaskan pincushion plant, is a mat or low mound forming perennial subshrub. The plants form low cushions or mats about 2-5 cm high and do not take a tussock-forming growth pattern. The branches, which can either be procumbent or decumbent, often root adventitiously and the proximal portions of the stems may contain persistent leaf remnants.

The leaves are evergreen and densely packed, with lengths varying from 3 to 12 mm. They are obovate to spatulate-elliptic in shape, with narrowly revolute margins. The leaves, similar to D. lapponica, are often herbaceous, sometimes having a narrow hyaline flange. It is the dense arrangement of the leaves that gives the plants a characteristic mat-like appearance.

The flowers emerge from pedicels that are 5-20 mm long, which can elongate to 30-50 mm. Flowers have four to seven sepals that are 4-7 mm long, and a corolla that is 7-9 mm, with lobes usually appearing white, sometimes light pink or rose. The flowers are perfect (bisexual). Each flower has 5 stamens with yellow anthers. The stamen filaments are glabrous (free from hair). The ovary is superior with a single stigma and style. The fruit is a capsule, 3-4 (up to 6) mm in diameter.

The taxonomy of D. obovata has been a subject of debate in the botanical community. Previously, it was considered a subspecies of D. lapponica, as D. lapponica var. obovata, and was also recognized as D. lapponica subsp. obovata. However, consistent differences in morphology, especially growth form and leaf shape, between D. obovata and D. lapponica, along with their largely non-overlapping geographical distributions, has led to D. obovata now being recognized as a distinct species. Notwithstanding these differences, the two species can be difficult to distinguish, especially when not in bloom, as they inhabit similar environments and have similar leaf morphology. This has contributed to past misidentifications and continues to be a point of attention for botanists and wildflower enthusiasts.

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Uses

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

I found no food or medicinal uses for D. obovata or D. lapponica It is often desired for gardening, but very difficult to cultivate in non-alpine regions.

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Distribution and Habitat

Diapensia obovata is primarily distributed across northwestern North America, spanning regions such as Alaska, Yukon Territory, Northwest Territory, and British Columbia. Its range also extends into western Siberia and Japan in Asia.

Diapensia lapponica, also known as the pincushion plant, displays a broader distribution across the northern hemisphere, with strong presences in Scandinavia, Siberia, Japan, northern Iceland, the Greenland coast, and far northeastern Canada. There is also a small, isolated population in the UK, specifically near Glenfinnan in Scotland. However, the species is considered imperiled or critically imperiled in certain New England States, Ontario, and Manitoba.

Previously, D. lapponica was considered to be prevalent in Alaska according to the Global Biodiversity Information Facility (GBIF). However, a recent taxonomic reclassification, recognizing D. obovata as a distinct species rather than a subspecies of D. lapponica, has shifted this understanding. As a result, Flora of North America now excludes D. lapponica from Alaska, recognizing that these are actually D. obovata.

According to the Flora of the Canadian Arctic Archipelago, there are phenological differences between the two species. While D. lapponica typically blooms in June or August in New England and Newfoundland, it was found to lack the opportunistic reproductive behavior of other species. Meanwhile, D. lapponica subspecies lapponica and obovata have distinct distributions and physical differences. Subspecies lapponica, with its narrowly spatulate leaves, is found in eastern North America, extending from New England to Baffin Island, as well as in Greenland, Iceland, Scotland, Scandinavia, and the western Soviet arctic and subarctic. Conversely, subspecies obovata, characterized by its obovate leaves and a more ‘sprawling’ growth form, is found in eastern arctic and subarctic Siberia, Korea, Japan, Aleutian Islands, Alaska, and the Yukon. This adds further depth to the understanding of these plants’ distribution, taxonomy, and differing characteristics.

It is frequently found in tundra, alpine heath, subalpine meadows, slopes, and ridges, in both dry and moist areas as well as on gravel and silt run-off banks.

Classification

References and Further Reading

Guidebook

Field Guide to Alaskan Wildflowers, Pratt, Verna E. pg 73

Classification and Taxonomy

Diapensia obovata (F. Schmidt) Nakai Taxonomic Serial No.: 512231, ITIS Database

Diapensia obovata (F. Schmidt) Nakai, Canadensys

Map and Distribution

Diapensia obovata (F.Schmidt) Nakai, GBIF Database

D. lapponica L. Published in: L. In: Sp. Pl. 141. (1753)., GBIF Database

D. lapponica, NatureServe Explorer

Description and Information

Diapensia obovata (F. Schmidt) Nakai, Flora of North America

1. D. lapponica Linnaeus, Sp. Pl. 1: 141. 1753., Flora of North America

D. lapponica L. subsp. lapponica, Flora of the Canadian Arctic Archipelago

D. lapponica , Central Yukon Species Inventory Project