Polygonaceae-misc2018-05-06T10:37:50+00:00

Polygonaceae: Knotweed Family — Knotweeds and miscellaneous

Willow Weed – Persicaria lapathifolia

Blooms:

June–Oct

Plant Height:

10–100 cm

Flower Size:

Medium cluster

Origin:

Native

Habitat:

Moist places

Notes:

This has a tall stem, glabrous and reddish, ascending to erect.  Flowers are 4- (occasionally 5-) lobed, green-white to pink, in axillary or terminal, often nodding spikes. Leaves are narrowly to broadly lanceolate, < 12 cm long with long, tapered, sharp tips. Leaves may have dark blotches on their surfaces.  The stems have sheaths (ocrea), 4–24 mm long, brownish, glabrous or ciliate but without noticeable bristles.

Dotted Smartweed – Persicaria punctata

Blooms:

June–Nov

Plant Height:

15–100 cm

Flower Size:

Large cluster

Origin:

Native

Habitat:

Low moist places

Notes:

This is common around pond margins.  It has ascending to erect stems with narrow interrupted 5–20 cm long clusters of tiny 5-lobed, white, bell-shaped flowers. Leaves are lanceolate to lance-ovate or diamond-shaped and punctate (with pitted glandular dots), hence the species’ scientific name. The tops of the sheaths (ocrea) have bristly hairs.

Common Knotweed – Polygonum aviculare subsp. depressum

Blooms:

May–Nov

Plant Height:

10–50 cm

Flower Size:

Very small

Origin:

Europe

Habitat:

Disturbed places

Notes:

This is a common noxious weed that survives drought and appears to thrive even on compacted soils such as trails. It is low growing, often prostrate and forming small mats. The white flowers are tiny (3–5 mm). The leaves are bluish-green and appear slightly succulent. Note the fused stipules that form a sheath around the stem nodes.

Dune / Beach Knotweed – Polygonum paronychia

Blooms:

Mar–Sept

Plant Height:

10–100 cm

Flower Size:

Small cluster

Origin:

Native

Habitat:

Coastal dunes

Notes:

This can be either prostrate or shrubby with stems sometimes rooting at the nodes. Leaves are 1–2 cm, linear to lanceolate, cauline only and mainly clustered around the stem tips. Leaf margins are rolled under. The flowers are in clusters in the leaf axils with pink and white overlapping lobes.

Woodland Threadstem – Pterostegia drymarioides

Blooms:

Mar–July

Plant Height:

Stem 10–40 cm

Flower Size:

Very small

Origin:

Native

Habitat:

Shady, sandy or gravelly places

Notes:

This is a prostrate or climbing plant usually found in shaded areas or beneath other plants. The leaves are small (2 cm wide), distinctively heart-shaped with a notch at the tip, opposite and either green or red. Stems and leaves are hairy. The perianth is tiny (< 2 mm), star-like, yellow or pink to rose with 5 (occasionally 6) lobes.