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Diarrhena obovata
Beak grass Taxonomy
Synonyms: Diarrhena americana obovata Subspecific taxa: Classification: Other taxonomic & nomenclature sources: USDA Plants; ITIS; The Plant List; IPNI Species Distribution
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County Map Legend
Absent: Not known from county Medium confidence: Medium or unknown confidence; often old records or unverifiable observations Medium-high confidence: Often observations by expert botanists High confidence: Often vouchered herbarium records Planted / introduced: Native species introduced outside historic range, or only in planted locations within county (e.g., restorations) Historic / extirpated: Only historic records for the species; likely extirpated (Note that this category is not yet functional) North American distribution maps for this species: FLNA; USDA Plants; BONAP; BISON
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Species Status
Status/Listing: No Information Notes: Origin: Native
Species Description
General: Monocot, perennial Roots: adventitious, rhizomes Shoots: alternate leaf arrangment; simple leaf type; entire leaf margin; Parallel leaf venation; awl-shaped leaf shape Inflorescence: panicle Flowers: perfect; 3 merous; complete; hypogynous ovary position Fruit: grain Physiology: autotrophic Reproduction: vegetative
Ecology & Natural History
Habitat: Species is distributed in low, shaded woods; moist ledges, and base of limestone cliffs. ILPIN Notes: These plants peep their shining dark green foliage well into winter and species is recommended as a ground cover in shady gardens and slopes. Species has a distinctive "bottle-shaped" grain (beaked caryopsis). Versus var. americana, this plant is smaller and glabrous. According to one author, this is "one of the more handsome woodland grasses." Species is found throughout Illinois except in northeast corner. Functional Relationships:
Human Relationships:
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Coefficient of Conservatism (C-value) [?] :
Comments & Questions
IL Plant Response: We have two species recorded for Illinois (D. americana and D. obovata).
For a long time it was thought that Diarrhena americana was restricted to southern Illinois, while D. obovata was statewide (Mohlenbrock 1986, 2002, 2014; Brandenburg in FNA 2007). Now we are starting to see collections labeled as D. americana throughout Illinois. Thus, the distribution of these species in Illinois may still need clarification. It is possible that these more recent records of D. americana in the northern part of the state are planted or introduced from the horticultural trade. The distribution map for D. americana on the Illinois Plants website is currently not accurate because it includes old records of Diarrhena that were made before these species were recognized as being distinct. Therefore, these older records contain both species under single name that cannot be separated. We hope to fix this problem. As far as identification, previous floras have used sheath pubescence to separate these species, but newer treatments do not consider that to be a good character. The size and shape of the lemma does seem to be consistent, although it is slightly overlapping. Other distinguishing features from the genus revision by Brandenburg et al. 1991, published in the Bulletin of the Torrey Botanical Club can be found here. https://drive.google.com/file/d/0B4jvvuRQu7l1dWVkNUJjWVhNSms/view?usp=sharing Diagrams of D.obovata showing the abruptly tapering apex of the lemma and beak of the caryopsis can be seen here: https://drive.google.com/file/d/0B4jvvuRQu7l1a3A5Zkk4empxWFU/view?usp=sharing https://plants.usda.gov/java/largeImage?imageID=diam_001_avd.tif Here are pictures of D.obovata showing the lemma and the bottlenosed beak of the caryopsis (photo credit P. Marcum, Champaign, IL). https://drive.google.com/file/d/0B4jvvuRQu7l1UEVlTU5uNFBsSkE/view?usp=sharing https://drive.google.com/file/d/0B4jvvuRQu7l1TjhNQzZXanZ4SVk/view?usp=sharing (Note: This response was originally posted on the Midwest Graminoids- Grasses, Sedges, and Rushes Facebook group page, P. Marcum & G. Spyreas)
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Illinois Natural History Survey - University of Illinois
Which species of Diarrhena am I seeing in the Chicago area?