Cortusa is a genus that consists of 19 species of delicate, hardy, alpine perennials, relative to "Primula" both in general appearance and habit of growth.
 The genus is named by the herbalist Matthiolus after his friend Cortusus, professor of botany at Padua, who discovered the plant called today "Cortusa matthioli".
 The plants are flowering herbaceous perennials native to the mountains of southern and eastern Europe, including the Alps and the Carpathians, and some species native to China.
 Most of the species are small spring bloomers for shade and rock garden.
 These low-growing and rather handsome little plants have clumps of downy, light green, heart-shaped leaves with serrated edges.
 In late spring, small loose umbel of delicate bell-shaped to lily-liked flowers born terminally on drooping spikes arise from the base, some 6-8in high.
 Flowers are magenta, pink, white and yellow.
 They are dormant in some months, and as spring begins, stems and leaves quickly start to reproduce.
Mirabilis nyctaginea is a species of flowering plant in the four o'clock family known by several common names, including wild four o'clock, heartleaf four o'clock, and heartleaf umbrella wort.
Mirabilis multiflora is a species of flowering plant in the four o'clock family known by the common name Colorado four o'clock.
 It is native to the southwestern United States from California to Colorado and Texas, as well as far northern Mexico, where it grows in mostly dry habitat types in a number of regions.
 It is a perennial herb growing upright to about 80 cm in maximum height.
 The leaves are oppositely arranged on the spreading stem branches.
 Each fleshy leaf has an oval or rounded blade up to 12 cm long and is hairless or sparsely hairy.
 The flowers occur in leaf axils on the upper branches.
 Usually six flowers bloom in a bell-shaped involucre of five partly fused bracts. Each five-lobed, funnel-shaped flower is 4 to wide and magenta in color.
Mirabilis alipes is a species of flowering plant in the four o'clock family known by the common name winged four o'clock.
 It is native to the southwestern United States from eastern California to western Colorado, where it grows in brush, woodland, and dry mountain slope habitat.
 It is a perennial herb growing in a clump near 40 cm tall and up to 80 cm wide.
 The leaves are oppositely arranged on the spreading stem branches.
 Each fleshy leaf has an oval or rounded blade up to 7 to long and is hairless or sparsely hairy.
 The flowers occur in leaf axils on the upper branches.
 Five to nine flowers bloom from a cup-shaped involucre of several partly fused bracts. Each five-lobed flower is about 1.5 cm wide and magenta in color; cream-colored flowers are also known.
Mirabilis macfarlanei is a rare species of flowering plant in the four o'clock family known by the common name MacFarlane's four o'clock.
 It is native to Idaho and Oregon in the United States, where it is only known from three river canyons.
 It faces a number of threats and is federally listed as a threatened species of the United States.
Mirabilis rotundifolia is a species of flowering plant in the four o'clock family known by the common name roundleaf four o'clock.
 It is endemic to Colorado in the United States, where it is limited to the south-central part of the state.
 It occurs in the Arkansas River Valley in Fremont, Pueblo, and Las Animas Counties.
Leucojum is a small genus of bulbous plants native to Eurasia belonging to the Amaryllis family, subfamily Amaryllidoideae.
 As currently circumscribed, the genus includes only two known species, most former species having been moved into the genus "Acis".
 Both genera are known as snowflakes.
Mirabilis jalapa, the marvel of Peru or four o'clock flower, is the most commonly grown ornamental species of "Mirabilis" plant, and is available in a range of colours.
 "Mirabilis" in Latin means wonderful and Jalapa is the capital of Veracruz México.
 "Mirabilis jalapa" was cultivated by the Aztecs for medicinal and ornamental purposes.
Mirabilis is a genus of plants in the family Nyctaginaceae known as the four-o'clocks or umbrellaworts.
 The best known species may be "Mirabilis jalapa", the plant most commonly called four o'clock.
Welwitschia is a monotypic gymnosperm genus, comprising solely the distinctive "Welwitschia mirabilis".
 The plant is commonly known simply as welwitschia in English, but the name tree tumbo is also used.
 It is called "kharos" or "khurub" in Nama, "tweeblaarkanniedood" in Afrikaans, "nyanka" in Damara, and "onyanga" in Herero.
 "Welwitschia" is the only living genus of the family Welwitschiaceae and order Welwitschiales, in the division Gnetophyta.
 Informal sources commonly refer to the plant as a "living fossil".
 "Welwitschia mirabilis" is endemic to the Namib desert within Namibia and Angola.

Question: Which genus is known for a plant called four o'clock, Mirabilis or Leucojum?
Answer: Mirabilis