Twenty-third Annual Meeting. 77 



morning. A still larger and more remarkable flower (CEnothera missouriensis), not 

 found in gardens, but on the rocky hills of eastern Kansas, opens more promptly 

 at 7 o'clock, or just about sunset. A smaller-flowered species (CE. sinuata) opens 

 earlier, or about 6 o'clock. The handsome white evening primrose, so common in 

 the streets of Topeka in the summer-time, and that keeps its flowers open so nicely 

 all day, I have not yet learned when they open, as I have never yet had the pleasure 

 of seeing one unfold its petals. But there are numerous species that open during 

 the day, and it is to be noted that each species has its own regular time for opening. 



The gauras, belonging to the same family, are just as regular in their habits. 

 Gaura coccinea, the scarlet gaura, opens at 6 o'clock in the evening, is a pure white 

 all night, and changes to a beautiful rose-color at daylight; which color deepens 

 slightly until early afternoon, when the flower wilts. Gaura biennis, a tall weed with 

 long, slender, far-reaching branches, opens its pure white flowers an hour after dark, 

 from 8 to 9 in the evening, and remains open until about 10 o'clock next day, still 

 very white, but changing slightly to rose-color before fading. Gaura parviflora, known 

 by its soft, silky leaves, opens at the same hour, closes a little earlier, and changes 

 strongly to rose-color before fading. 



How many have noticed our common jimson (Datura stramonium) opening 

 from 5 to 6 o'clock every evening? Just as regularly it closes early in the morning. 

 Several of our cultivated jimsons (Datura metel, etc.), with their beautiful large 

 white flowers and delightful fragrance, open very promptly at sunset, and close 

 just as regularly in early morning. 



Another group of flowers noted for their great regularity is our wild four-o'clocks. 

 The common kind, with the large, heart-shaped leaves (Oxybaphus nyctagineus), 

 opens its flowers very regularly every afternoon at 4 o'clock, even much more regu- 

 larly than the four-o'clock of the gardens. Another ( 0. angustifolius), with a deeply- 

 lobed white calyx, opens at 5 o'clock, or from that to 6. All the species of Oxybaphus 

 open late in the afternoon. Abronia fragrans, a handsome sand-hill plant of the 

 same order, opens at 6 in the evening. 



Another plant of an order allied to the morning glories, and with a strong tend- 

 ency to periodicity, is Heliotropium convolvulaceum, which is common on the sandy 

 plains of southwestern Kansas, and spreads its sweet-scented white trumpet flowers 

 in early twilight. 



Several plants of an order allied to the evening primroses, and somewhat to the 

 poppies, are periodic in the time of opening their flowers. Mentzelia oligosperma 

 opens early in the morning and closes about one o'clock in the afternoon. Ment- 

 zelia nuda, with remarkably large, creamy-white flowers, opens at three o'clock in 

 the afternoon, with its buds all turned toward the southwestern sky, so that the 

 flowers open directly in the face of the sun, just as the daily temperature has begun 

 to decline. Mentzelia ornata, with still larger, yellowish-white flowers, opens an 

 hour or two later. Both of these close early next morning, and remain asleep all 

 day to reopen in the afternoon. 



The regularity of opening of many members of the chickweed and purslane 

 families is well known, the former flowers opening in the evening, the latter in the 

 morning. Somewhat allied to this last is the cactus family, the regularity of 

 blooming in certain members of which is well known. 



These observations, with others unmentioned, may be tabulated into what may 

 be called 



A FLORAL CLOCK FOE KANSAS. 



2 to 3 A. M. . . .Convolvulus sepium; closes next evening. 



3 A. M Ipomcsa lacunosa ; closes about 2 p.m. 



