Fairly regularly as I hiked the arroyo's most isolated reaches, along with endless plastic bottles washed from trash dumps far upstream, I found invasive plants looking in surprisingly good health. One such weed was the scarlet-flowered Lion's Ear, LEONOTIS LEONURUS, which I told you about in this month's February 9th Newsletter. Lion's Ear is from Southern Africa.
Another common invasive was the attractive Castorbean, RICINUS COMMUNIS, from whose beans castor oil is pressed, and whose bean shells contain ricin, one of the most deadly of poisons. This plant, often advertised in the backs of magazines under the name of Mole Killer, also is from tropical Africa.
There was a lot of Tree Tobacco, NICOTIANA GLAUCA, too. The genus Nicotiana is the same in which the tobacco of cigarette fame is found, so in a sense this is a real tobacco, though the plant doesn't contain nicotine. The species is originally from southern Bolivia and northern Argentina but has vigorously invaded some parts of the US Southwest and other countries -- it's even been found growing wild in North America as far north as Ohio and Maryland. One reason it's invading so many places is that people grow it for its pretty flowers. Here I often see it around people's homes grown as an ornamental, and along streams. You can see it below: