Oenothera serrulata is a species of flowering plant in the Onagraceae known by the common name yellow sundrops. Other common names include halfshrub sundrop,Calylophus serrulatus. USDA NRCS Plant Fact Sheet. serrate-leaved evening primrose, shrubby evening primrose, plains yellow primrose, and halfleaf sundrop.Calylophus serrulatus. Missouri Botanical Garden. It is native to central North America, including central Canada and the central United States.
This plant is a subshrub that branches and forms a bushy clump up to tall. The toothed leaves are up to long. The yellow flowers bloom between March and November and have four petals. They open in the morning and close in the afternoon. They fade orange or pink with age. The fruit is a cylindrical capsule. It grows in dry, open plains and prairies.
This drought- and heat-tolerant species grows in many types of substrate, including caliche, limestone, and gypsum. The leaves turn so that their edges face the sun, an adaptation to hot conditions.
Taxonomy Oenothera serrulata was scientifically described and named by Thomas Nuttall in 1818. It is classified in the genus Oenothera within the Onagraceae family. It has no accepted subspecies or varieties, but it has synonyms according to Plants of the World Online.
Table of Synonyms Name Year Rank Notes Calylophus australis 1970 species = het. Calylophus drummondiana 1835 species = het. Calylophus nuttallii 1835 species ≡ hom., nom. superfl. Calylophus serrulata 1964 species ≡ hom. Calylophus serrulata var. arizonicus 1964 variety = het. Calylophus serrulata var. spinulosus 1964 variety = het. Meriolix drummondiana 1903 species = het. Meriolix intermedia 1903 species = het. Meriolix oblanceolata 1931 species = het. Meriolix serrulata 1819 species ≡ hom. Meriolix serrulata var. douglasii 1843 variety = het. Meriolix serrulata var. drummondii 1843 variety = het. Meriolix serrulata var. nuttallii 1843 variety ≡ hom., not validly publ. Meriolix serrulata var. spinulosa 1896 variety = het. Meriolix spinulosa 1895 species = het. Oenothera leucocarpa 1830 species = het. Oenothera serrulata var. douglasii 1908 variety = het., nom. illeg. Oenothera serrulata var. douglasii 1840 variety = het. Oenothera serrulata subsp. drummondii 1965 subspecies = het. Oenothera serrulata var. drummondii 1840 variety = het. Oenothera serrulata f. flava 1929 form = het. Oenothera serrulata var. integrifolia 1908 variety = het. Oenothera serrulata var. nuttallii 1840 variety = het. Oenothera serrulata var. oblanceolata 1939 variety = het. Oenothera serrulata var. spinulosa 1840 variety = het. Oenothera serrulata var. typica 1929 variety ≡ hom., not validly publ. Oenothera spinulosa 1840 species = het. Notes: ≡ homotypic synonym; = heterotypic synonym
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