Overview

Comprehensive Description

Comments

This wildflower resembles a dwarf version of the better-known Hypericum spp. (St. John's Wort species). Other small-flowered Hypericum spp. (flowers 1/3" across or less) usually have more narrow leaves and therefore are easily distinguished from Dwarf St. John's Wort. An exception is Hypericum boreale (Northern St. John's Wort), which is rare in Illinois. Generally, Northern St. John's Wort can be distinguished from Dwarf St. John's Wort and other small-flowered species in this genus by its leafy floral bracts, which resemble small leaves. It also has purple seed capsules that are as long or longer than its sepals. Dwarf St. John's Wort, in contrast, has tiny scale-like floral bracts and its seed capsules usually remain green for a longer period of time.
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Description

This native wildflower is either a short-lived perennial or summer annual. It is usually a short bushy plant about 4–18" tall, although larger specimens have been reported. The much-branched stems are light to medium green, glabrous, sometimes glaucous, 4-angled or terete, and sometimes narrowly winged. The opposite leaves are about ½–1½" long, ¼–¾" across, and sessile; they are medium green, broadly oblong to oval in shape with 1-5 prominent veins, smooth among their margins, and glabrous. The upper stems terminate in small clusters (cymes) of flowers. Individual flowers are ¼" across, consisting of 5 yellow to yellow-orange petals, 5 green sepals, a light green pistil with 3 styles, and 5-15 stamens. The petals and sepals are about the same length; the petals are oblong, while the sepals are linear-oblong. The peduncle and pedicels of the flowers are light to medium green, slender, and glabrous; sometimes there are small scale-like bracts near the area where two pedicels diverge. These bracts are linear-lanceolate in shape and much smaller in size than the leaves. The blooming period occurs from mid-summer to early fall and lasts about 2-3 months. Usually, only a few flowers are in bloom at the same time. Each flower is replaced by an ovoid seed capsule that becomes up to 1/3" tall at maturity; this glabrous capsule has remnants of the styles at its apex and it is 3-celled. Each cell of the capsule contains numerous tiny seeds that are dark-colored, narrowly oblongoid, and somewhat flattened. The persistent sepals become enlarged as the seed capsules mature; the sepals are usually about the same length or a little longer than full-sized capsules. This wildflower reproduces by reseeding itself.
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Source: Illinois Wildflowers

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Distribution

National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Range and Habitat in Illinois

Dwarf St. John's Wort is occasional in most areas of Illinois, otherwise it is uncommon or absent (see Distribution Map). Habitats include sandy forests in floodplain areas, sandy swamps, wet to moist sand prairies, gravelly seeps and springs with an acidic bedrock (e.g., sandstone), damp depressions in sandstone glades, damp depressions along sandstone cliffs, low sandy areas along rivers and ponds, damp depressions in sandy paths, and abandoned sandy fields. This wildflower is found in both disturbed and little-disturbed habitats.
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Localities documented in Tropicos sources

Hypericum collinum var. liebmannii R. Keller:
Mexico (Mesoamerica)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Localities documented in Tropicos sources

Hypericum myrianthum subsp. tamariscinum (Cham. & Schltdl.) N. Robson:
Brazil (South America)
Uruguay (South America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
  • Robson, N. K. B. 1990. Studies in the genus Hypericum L. (Guttiferae). 8. Sections 29. Brathys (part 2) and 30. Trigynobrathys. Bull. Brit. Mus. (Nat. Hist.), Bot. 20(1): 1–151.   http://www.tropicos.org/Reference/24483 External link.
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Localities documented in Tropicos sources

Hypericum mutilum var. parviflorum Fernald:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Localities documented in Tropicos sources

Hypericum stellarioides Kunth:
Colombia (South America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Localities documented in Tropicos sources

Hypericum parviflorum A. St.-Hil.:
Brazil (South America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Localities documented in Tropicos sources

Hypericum mutilum L.:
Argentina (South America)
Azores (Africa & Madagascar)
Brazil (South America)
Canada (North America)
Colombia (South America)
Ecuador (South America)
Honduras (Mesoamerica)
Italy (Europe)
Mexico (Mesoamerica)
New Zealand (Oceania)
Peru (South America)
Poland (Europe)
Paraguay (South America)
Uruguay (South America)
United States (North America)
Caribbean (Caribbean)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
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Physical Description

Type Information

Isotype for Hypericum mutilum var. latisepalum Fernald
Catalog Number: US 11320
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): A. H. Curtiss
Locality: Duval, Florida, United States, North America
  • Isotype: Fernald, M. L. 1936. Rhodora. 38: 372.
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Ecology

Habitat

Range and Habitat in Illinois

Dwarf St. John's Wort is occasional in most areas of Illinois, otherwise it is uncommon or absent (see Distribution Map). Habitats include sandy forests in floodplain areas, sandy swamps, wet to moist sand prairies, gravelly seeps and springs with an acidic bedrock (e.g., sandstone), damp depressions in sandstone glades, damp depressions along sandstone cliffs, low sandy areas along rivers and ponds, damp depressions in sandy paths, and abandoned sandy fields. This wildflower is found in both disturbed and little-disturbed habitats.
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Source: Illinois Wildflowers

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Associations

Faunal Associations

The flowers are cross-pollinated primarily by small bees, which collect pollen. Some flies may visit the flowers to feed on the pollen. Nectar is not available as a floral reward. There are a small number of insects that feed on various parts of Hypericum spp. (St. John's Wort species). These insect feeders include the caterpillars of several moths, some leaf beetles, the aphid Brachysiphum hyperici, and the caterpillars of the butterfly Strymon melinus (Gray Hairstreak). See the Insect Table for a listing of these insect species. Mammalian herbivores usually avoid consumption of the foliage because of its toxicity. The foliage contains hypericin, which produces a photosensitive reaction to sunlight, particularly in light-skinned animals. Photographic Location
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Hypericum mutilum

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
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Conservation

Conservation Status

NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

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Relevance to Humans and Ecosystems

Benefits

Cultivation

The preference is full sun to light shade, wet to moist conditions, and acidic soil that is either sandy or rocky.
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Wikipedia

Hypericum mutilum

Hypericum mutilum is a species of St. John's wort known by the common name dwarf St. John's wort. It is native to parts of North America, and is present in other parts as an introduced species. It is an annual or perennial herb taking a multibranched erect form up to about 60 centimeters tall. The oval green leaves are one or two centimeters long and are covered in tiny glands. The inflorescence is a compound cyme of tiny flowers. Each flower has five yellow to orange-yellow petals 2 millimeters in length and five green sepals which are slightly longer. At the center of the flower are many whiskery stamens. The fruit is a capsule a few millimeters wide containing many seeds.

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