1 The sun's rays are strongest during the hours of 10 a.m. to 4 p.m. The sun's rays are also stronger at higher altitudes and lower latitudes (closer to the tropics). Reflection off water, sand, or snow can make the sun's burning rays stronger.  Sun lamps can cause severe sunburn.
Division Marchantiophyta&#151Liverworts, genus Marchantia. : The thallus of the haploid gametophyte (n) grows flat on moist ground, and it is many-cells thick. Pores to permit gas exchange are in the top surface, and there are air spaces within the top zone of the thallus. Water is absorbed throughout the surface.
For other uses, see Zinnia (disambiguation). Zinnia is a genus of plants of the sunflower tribe within the daisy family. They are native to scrub and dry grassland in an area stretching from the Southwestern United States to South America, with a centre of diversity in Mexico. Members of the genus are notable for their solitary long-stemmed flowers that come in a variety of bright colors.