The stems are usually trailing and branched at the base, sometimes forming clumps two or more feet broad. The leaves are quite variable in shape but are generally oblong and narrowed at the base, with margins ranging from entire to deeply lobed and divided.
The group name honors Emanuel Hartmann of Louisiana; “tetraptera” is from the Greek meaning “four-winged” and refers to the shape of the seed-capsule. The plants in this group are sometimes placed with the yellow evening-primroses of the Œnothera group, but characteristics other than color separate them.
Showy Primrose (_Hartmannia speciosa_) is a large-flowered white primrose found on plains and prairies from North Texas to Missouri. The seed-capsules are narrowed at the base but are not stalked, and the calyx tube is longer than the capsule.
Rose Primrose (_Hartmannia rosea_) is a small-flowered primrose found in Southern and Southwestern Texas and Mexico. The flowers are small, an inch or more broad, with rounded deep-pink petals. The calyx tube is much shorter than the long-stalked capsule.
Missouri Primrose. Flutter-Mill. Broad-Winged Evening-Primrose (_Megapterium missouriense_) clings to the side of a gravelly cliff or grows on rocky limestone hillsides from Missouri to Colorado and Texas. The flowers bloom in Texas in April and May, opening in the afternoon and closing the next morning. The plants grow in low clumps about a foot high. Numerous flowers are borne on the stem along with the slender leaves. Four broad yellow petals make up the cup-shaped portion of the flower above the slender calyx-tube, which is 4-6 in. long. The seed-capsules at the base of the flower develop four broad papery wings and reach at maturity a width of 3 in. These broad wings are responsible for the scientific name of the plant. The capsules are easily blown about by the wind, and the seeds are widely scattered.
The evening-primroses usually produce large, thready masses of pollen. Every child is initiated into a buttercup fraternity at some period in his life by being invited to smell of the flower and having his nose smeared with the profuse pollen.
Square-Bud Primrose. Day Primrose. Creamcups (_Meriolix spinulosa_) has yellow cup-shaped flowers which last only twenty-four hours but which are open during the day. It may readily be distinguished from other evening-primroses by the slender woody stems which soon become reddish or straw-colored. The stems grow 1-1½ ft. high with clusters of flowers at the top. The flowers are nearly two inches broad and have four petals. The short, broad sepals are winged on the back and make the buds appear square and pointed.