# Davis' Knotweed (*koenigia davisiae*) Davis' Knotweed (Koenigia davisiae) is a resilient, low-growing perennial herb native to the high-elevation regions of the western United States. Thriving in the harsh, rocky environments of the Cascade Range and the Sierra Nevada, this alpine specialist has adapted beautifully to life on shifting talus slopes and sterile volcanic pumice. It forms sprawling, leafy mats that stabilize loose mountain soils, making it an ecological anchor in fragile alpine ecosystems. What makes this plant particularly captivating is its striking seasonal transformation; throughout the summer it maintains a low profile with yellowish-green leaves, but as the autumn chill sets in, the entire plant blazes into shades of brilliant orange, red, and purple, painting the high-altitude landscapes in fiery hues. - **Category:** [Plants](https://www.snappit.app/explore/categories/plant) - **Rarity:** Common - **Danger:** 1/5 · Very low - **Snaps:** 2 - **Habitat:** Found on high-elevation alpine scree, rocky talus slopes, and volcanic pumice fields, typically between 1,500 and 3,300 meters in elevation. ![Davis' Knotweed](https://inaturalist-open-data.s3.amazonaws.com/photos/4329384/medium.jpeg) Photo: Ken-ichi Ueda, CC BY 4.0 · [iNaturalist](https://www.inaturalist.org/photos/4329384) ## Appearance Davis' Knotweed typically grows in sprawling, multi-branched clumps that reach 10 to 40 centimeters in height. Its fleshy, oval-shaped leaves are yellowish-green to bright green, with smooth or slightly hairy margins, and are arranged alternately along thick, fleshy stems. The flowers are tiny, clusters of inconspicuous yellowish-green, cream, or purplish-white blossoms nestled in the leaf axils. In late summer and autumn, the entire plant undergoes a dramatic color shift, turning a vibrant, fiery orange-red that stands out vividly against grey volcanic gravels and granite scree. ## Taxonomy - **Kingdom:** Plantae - **Phylum:** Tracheophyta - **Class:** Magnoliopsida - **Order:** Caryophyllales - **Family:** Polygonaceae - **Genus:** Koenigia ## Interesting facts - By holding down loose, sandy gravels on steep mountain ridges, this plant acts as a natural erosion-control agent in fragile subalpine zones. - It thrives in some of the most barren environments in North America, including the stark volcanic ash fields around Mount Shasta and Mount Lassen. - The species is named in honor of Nancy Jane Davis, a 19th-century American botanist and educator who contributed significantly to early collections of western flora. ## Special abilities - **Pumice Pioneer:** Exhibits extreme tolerance to nutrient-poor, porous volcanic ash and shifting soils where few other plants can establish roots. - **Anthocyanin Shield:** Accumulates red pigments in autumn, protecting its cellular machinery from intense high-altitude ultraviolet radiation and freezing temperatures. - **Deep Taproot Anchor:** Develops a thick, woody taproot that penetrates deep into unstable talus slopes to anchor the plant and access subterranean moisture. ## Measurements & details - **Length:** 10-40 cm - **Lifespan:** 5-25 years ## Diet & Feeding As a photosynthetic plant, Davis' Knotweed produces its own energy using sunlight, water, and carbon dioxide, while absorbing essential minerals through its root system. - **Primary Foods:** Sunlight, Carbon dioxide, Water, Soil minerals ## Ecological connections - **Eaten by:** American Pika (*Ochotona princeps*) — Provides a crucial autumn food source, with its foliage gathered and dried for winter haypiles by alpine rodents. - **Mutualism:** Western Bumblebee (*Bombus occidentalis*) — Flowers are pollinated by high-altitude bees seeking nectar in the sparse alpine environment. - **Host plant:** Lustrous Copper (*Lycaena cupreus*) — Serves as a host plant and food source for the caterpillars of high-altitude butterflies. ## Safety **Danger:** 1/5 · Very low No special safety notes yet. ## Frequently Asked Questions ### How to identify Davis' Knotweed? Start with the whole plant, then compare leaf arrangement, leaf edges, stems and any flowers or fruit. Opposite leaves grow in pairs; alternate leaves come one at a time along the stem. These details tell you far more together than a single green leaf does. Plant Identifier: upload a photo and compare the visible details. ### How long is Davis' Knotweed? 10-40 cm ### How long does Davis' Knotweed live? 5-25 years ### What does Davis' Knotweed eat? As a photosynthetic plant, Davis' Knotweed produces its own energy using sunlight, water, and carbon dioxide, while absorbing essential minerals through its root system. ### Where is Davis' Knotweed usually found? Found on high-elevation alpine scree, rocky talus slopes, and volcanic pumice fields, typically between 1,500 and 3,300 meters in elevation. ## Where to spot - [Rim Village Historic District](https://www.snappit.app/guides/places/rim-village-historic-district) — Oregon, US · Historic District - [Lassen Volcanic National Park Highway Historic District](https://www.snappit.app/guides/places/lassen-volcanic-national-park-highway-historic-district) — California, US · Historic District - [Munson Valley Historic District](https://www.snappit.app/guides/places/munson-valley-historic-district) — Oregon, US · Historic District - [Sunrise Historic District](https://www.snappit.app/guides/places/sunrise-historic-district) — Washington, US · Historic District - [Yakima Park Stockade Group](https://www.snappit.app/guides/places/yakima-park-stockade-group) — Washington, US · Historic District [View all places to see Davis' Knotweed](https://www.snappit.app/guides/where-to-see/davis-knotweed) ## More Plants - [white snakeroot](https://www.snappit.app/explore/white-snakeroot) (*Ageratina altissima*) - [tree-of-heaven](https://www.snappit.app/explore/tree-of-heaven) (*Ailanthus altissima*) - [western sword fern](https://www.snappit.app/explore/western-sword-fern) (*Polystichum munitum*) - [common milkweed](https://www.snappit.app/explore/common-milkweed) (*Asclepias syriaca*) --- Source: [Davis' Knotweed: Facts & Places to See — Snappit](https://www.snappit.app/explore/davis-knotweed)