The following discussion begins with the floras of the Maastrichtian stage of the Upper Cretaceous, 70--65 Ma, and progresses forward in time through the Tertiary to 2 Ma, the end of the Pliocene epoch, i.e., to the advent of the Pleistocene, the "Ice Ages." Within each section, the fossil floras are discussed in a sequence that begins with the southeastern corner of the continent and proceeds westward and around the continent in a clockwise fashion.
In describing paleoevents, degrees of latitude and longitude, unless otherwise noted, are given in terms of present-day locations of the poles and continents, even though the North American continent has moved slightly relative to the poles during the Tertiary and to the present.
The flora of North America includes a large number of conspicuous plants that are called "weeds." The concept of weed is not precisely defined, for it has both a sociological and a biological component. From the sociological perspective, a weed is simply a plant that is growing where someone wishes it were not, and therefore, a weed may be regarded casually as a "plant-out-of-place." By that definition, a rose growing in a wheat field would be a weed; a rose in a garden would not. Some plants, however, have the genetic endowment to inhabit and thrive in places of continual disturbance, most especially in areas that are repeatedly affected by the activities of humankind. These plants are biologically "weedy," and they are sometimes termed colonizing or invasive plants. These biological weeds are the focus of next paragraph.
Weeds have a measurable effect on the affairs of society, and therefore they have attracted much attention. Weeds occur in all growth forms and in many lifestyles. The majority of weeds are flowering plants, and a high proportion of them share some or all of the following characteristics: short life cycle, rapid growth rate, high level of energy allocated to reproduction, efficient dispersal mechanisms, high population growth rate, wide distribution, seeds with long life spans, and flexible use of environmental resources. He noted that a plant with but few of these attributes is less likely to be successful as a weed than is a plant with all or most of them; therefore, the variation ranges from casual, local weeds to aggressive, widespread weeds.
The most troublesome and aggressive weeds are those foreign or alien species that have invaded the North American continent from regions elsewhere in the world. By comparison, fewer and less aggressive weeds are native species. Analysis of the geographical components of a large number of weeds usually shows over 60% to be foreign species. The distinction between foreign species and native species is not always clear, and it is not easy to measure the impact of those foreign or alien plants on the native vegetation. Several factors contribute to this lack of precision.
Botanists assume that species have a "place of origin," where at some time the species are differentiated from the ancestral entities. As time passes, a newly formed species migrates into new areas and/or expands its range, through the routine mechanisms of seed dispersal, seedling establishment, and other factors. Undoubtedly, some botanical traffic has occurred between North America and other continents since antiquity, but clearly colonization following Columbus's voyages to America initiated a significant number of invasions. Some of the historical aspects of plant migration at the hands of humankind are reviewed by V.Muhlenbach (1979).
Foreign or alien species are usually regarded as those that have been brought to North America by human activities in post-Columbian times, while native species either originated in North America or had arrived by various means in pre-Columbian times. Although botanists frequently use the term "introduced" for these foreign or alien species, in this chapter the term has a more restricted meaning and refers to those species deliberately brought by people into a new region, where the plants grow without cultivation. How many species have been transported from their putative places of nativity to North America in post-Columbian times is, of course, unknown. The historical documentation for these plant movements is often not well known or not yet researched, and many times what is known is based on circumstance and inference.
Here are en examples of native American plants. A large Sycamore tree, Platanus racemosa, played an early role in the establishment of Los Angeles. The central Gabrielino village of Yangna was located near a 60 ft. high, 200 ft. wide sycamore which was used for meetings amongst the Gabrielino leaders and was known as the "council tree". The Spanish settlement that later became the pueblo of Los Angeles was located next to Yangna, in sight of this stately tree. The settlement was washed away in the Great Flood of 1815, but the sycamore survived. It later died in 1892 and was cut down. A ring count revealed that the tree was 400 years old. It had started its life about the time Columbus first landed in America. Cottonwoods were very common trees along rivers and arroyos in California and the southwest. As cities and farmers have lowered water tables, these riparian trees have disappeared from many banks along arroyos in California, Nevada, and Arizona. The Fremont Cottonwood, Populus fremonti, was discovered in 1844 near Pyramid Lake by Major John Charles Fremont and Kit Carson. They used its riparian nature to help locate water. Willows are also a common riparian tree in the southwest. Some are actually assisted by floods. The rushing water bends some branches down into a sand bar where they sprout new roots and plants. The Willow, Salix, leaves were used by Native Californians for medicine. The small branches were used for baskets, and the large branches for wood. Cattail, Typha domingensis. California Indians used the roots and pollen for food, the roots for medicine, and the stalks for bedding and house construction material The Coastal Live Oak, Quercus agrifolia. An organization was created to promote its protection and replanting. Spiny Clotbur, Xanthium spinosum , uses its spines to transport the seeds long distance with the help of animals who brush against it. Gourds found in the Sepulveda Basin. During major winter storms these plants may be under the floodwaters that are held back by the dam.
Common Sunflower, Helianthus annuus.Native Californians used the seeds for food and the roots for medicine. Duckweed, and two Bluets, if you can see them. Bluets are common along the river. Reeds and grasses were used by native americans for baskets, cordage, and food from the seeds. Jimson Weed was used by Native Americans as a ritual drug. It can be poisonous to humans and animals.
Our next pages we will devote to the world of animals of USA. Which animals are really special for the North America? One of the is coyot. The ghosts of the woods. The ever present monolog. The infamous cries of the coyote sparks tremors of terror in rural dwellers. Few Westerners regard the Canis Latrans as anything more than a savage nuisances. But even its enemies concede its durability. It thrives in the face of all attempts to trap, poison, or blast it into oblivion. The settling of the Great Plains is expanding its range eastward to the Atlantic, partly because of extirpation of the wolf. New Englanders call it the "coy dog" or brush wolf. But it's still the same mythical coyote of lore and legend. The mane "coyote" comes from the Aztec word "coyotl." Its Latin name means "barking dog." Adults, 2 feet high at the shoulders, are 3.6 to 4.5 feet long and weigh 20 to 50 pounds. The tough and wiry appearance of the coyote is misleading to its keen senses and quick wit. The coyote adapts readily to almost any habitat. And it is fast--up to 30 miles an hour in a dead run. Coyotes hunt alone or team with others to scrounge a meal. They will eat anything--from rabbits, rodents, and carrion (most of their diet), to watermelons and insects. Coyotes mate for life, and the female bears five or six pups each spring, and both parents share in their upbringing.
The other is jaguarundi.Hued like the desert dusk, the long low-slung jaguarundi can stalk unseen in the half-light. Twilight and dusk are its most successful hunting times. This small-headed southern felid, in body composition, resemble the weasels about as much as it does fellow cats. Tail down, it moves sinuously through the brush with scarcely a ripple of leaf or twig to betray its presence. One pounce, and a bird in the brush is a bird consumed. Though an agile climber, this species spends less time in the trees then the ocelot. Preferring to hunt on the ground, it needs no leaf or limb pattern on its black or russet coat. Dark plain fur serves as more than adequate camouflage when hunting fish and small mammals. The jaguarundi is one of the least known cats on the continent, its life history and population not yet well documented, and now may be too late. Already a rare animal, it becomes even more rare as its habitat--wild thickets and lowland forests--is sheared for ranching and farm use. Mating time for this cat seems to vary with location. The litter of two to three kittens is born after a gestation period determined from captive animals to be 72 to 75 days. Like most other cats, kittens in the wild are probably cared for solely by their mother. Full grown, the jaguarundi stands up to 14 inches at the shoulders. Its tail accounts for nearly half its length of 35 to 55 inches. A large individual may weigh as much as 20 pounds.
The same cat spice as a jaguarundi is ocelot. Marbled to blend into their sun and shadow world, Ocelots wear