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Waterpepper is a rather spare plant, 1-2' tall which needs close observation to be appreciated. 2-7" long spikes of minute flowers, only a few of which are open at any one time, terminate the upper stems; the flower spikes often nod or droop. Each greenish-white flower is ~1/8" long with five tepals covered with glandular pits (see below), green towards the base, brilliant white at the tips, 4-6 white stamens, and 2-3 white styles. The flowers never open very far. P. hydropiper is distinguished by (usually) reddish stems and the presence of tiny glandular pits (often pale yellow or brown, and only visible with magnification) on the greenish portions of the tepals. Cultivated varieties of waterpepper have been eaten in Japan and Europe, but the wild form produces a variety of oils that can cause skin (including the oral mucosa) irritation and swelling.

Persicaria

Persicaria hydropiper

waterpepper [Blooms: Aug-Sep]

Pale smartweed is a very tall smartweed (2.5-4') characterized by long, dense, drooping, whitish flower clusters and the absence of bristles on the leaf sheaths (ocreae). Stems terminate in drooping flower spikes 2-8" long, densely packed with small (1/8" long) flowers. Individual flowers have 4-5 greenish-white to pinkish tepals, 5-6 stamens with pink anthers and two styles. Because the flowers open only at their tips, the reproductive structures are difficult to observe. After fertilization, a three-angled seed, 2 mm across, develops nestled in the tepals. This is the largest smartweed that occurs in Illinois. Pale smartweed prefers wet soils (e.g., the shores of water bodies). Pale smartweed is similar to Pennsylvania smartweed (Persicaria pennsylvanica) but that plant has erect, cylindrical flower spikes and the flowers are pink or reddish.

Persicaria

Persicaria lapathifolia

pale smartweed [Blooms: Jul-Oct]

Creeping smartweed is another weedy exotic, but its charm increases as you look closer. The flower spikes are 1.5" long and <1/4" wide; they are covered with tiny (~1/8" long) flowers with five pink tepals, only a few of which are open at any one time. (Petals are absent.) There are five stamens with pink or yellow anthers and three styles hidden within the flower; they are visible only with difficulty. At the base of each flower is a small membranous sheath with bristles as long or longer than the flowers (not present on all flowers). After fertilization, a three-angled seed that tapers to a point on each end develops nestled in the tepals. This is an Asian species that was introduced to North America around 1910 near Philadelphia and reached Illinois in the 1940's; it strongly prefers wet soils. Creeping smartweed resembles lady's-thumb (Persicaria maculosa), but creeping smartweed's sprawling habit and the long bristles associated with the flowers are distinctive.

Persicaria

Persicaria longiseta

creeping smartweed [Blooms: May-Oct]

Lady's-thumb is an exotic, native to Europe, but has a long history in North America — it was first reported from the Great Lakes in 1843. Flower spikes (racemes) are 1/2-1.5" long and densely covered with tiny (1/8" long) pinkish-white flowers; flower color is quite variable, even within a single flower spike. The flowers are "shy" and often open only at the tips of the 4 or 5 sepals (there are no petals); both the six stamens and the single style (divided into three towards the distal end) remain hidden. Seeds are black; they develop singly within the persistent sepals and remain largely hidden by the sepals; they can be found on flower heads still blooming. Lady's-thumb prefers wet habitats.

Persicaria

Persicaria maculosa

lady's-thumb [Blooms: Jun-Sep]

Pennsylvania smartweed flower spikes are 3/4-2" long, distinctly cylindrical with a blunt tip, erect, and densely covered with white, pink, or reddish flowers, only a few of which are open at any time. The peduncle of the flower spike is usually covered with short glandular hairs. Individual flowers are ~1/8" long, and have five tepals (white, light pink, or rose pink), 6-8 stamens with yellow, white, or pink anthers and two styles. Pennsylvania smartweed is a particularly variable species and may be difficult to identify unequivocally. If the stems zig-zag between nodes, if the flower stalks' peduncules are covered with glandular hairs, or if the flower spikes are short, cylindrical and erect, the specimen is likely to be Pennsylvania smartweed, but any or all of these features may be missing.

Persicaria

Persicaria pensylvanica

Pennsylvania smartweed [Blooms: Jul-Sep]

Dotted smartweed (Persicaria punctata) is a very common smartweed in Illinois wetlands. The upper stems produce spike-like racemes 2-6" long with white to greenish-white flower buds and flowers sparsely distributed along their length. Individual flowers are about 1/8" long with five white tepals covered with glandular depressions (best viewed with a hand lens). There are 6-8 stamens with red or pink stamens; the single style divides into two or three branches near its base. The flowers only open at their tips. The single seed is three-angled, oblong, and shiny brown to black; it remains tightly enclosed in the tepals as it develops. In Jackson Park, only dotted smartweed and waterpepper (Persicaria hydropiper) have glandular depressions on the surface of the flower tepals.

Persicaria

Persicaria punctata

dotted smartweed [Blooms: Aug-Sep]

A relative of the smartweeds and lady's thumb, jumpseed consist of a single, unbranched stem 1-2' tall with an apical inflorescence that can add an additional 16". Flowers are brilliant white, tiny (<3/16" across), with 4 sharply pointed petals (actually, sepals); 4-5 white stamens and a style are visible if you have really good eyesight. Flowers are widely spaced along the flower stalk on very short green stalks. Jumpseed is easy to tell from other smartweeds by the very long inflorescence with sparsely distributed flowers and very large leaves.

Persicaria

Persicaria virginiana

jumpseed [Blooms: Jul-Aug]