Several friends have visited China recently, and the gardeners among them have noticed that North America and China have many plant genera in common. Considering the vast ocean that separates us from Asia, these globetrotters were rightly mystified when they encountered magnolias, clematis, pines, walnuts, elderberries, and other familiar plants. . For centuries – until scientists developed better tools – botanists were also puzzled by the presence of these genera on distant continents.
The explanation is Pangea, a super-continent that intermittently held all of Earth’s landmasses. Finally, around 175 million years ago, Pangea broke away for good, with North America separating from Asia, India, Africa, Australia, and Australia. South America. Obviously, more fractures occurred, but only after the botanical connections of eastern North America and East Asia were forged.
Another mystery that had confused generations of botanists was the fertilization process of gingko (G. biloba), a primitive species and the only living example of a once numerous genus. Surprisingly, the breeding sequence was deciphered in 1896 by a botanical illustrator at the Tokyo Botanical Garden. This man – Hirase Skugoro – solved the puzzle through painstaking microscopic work, discovering that gingkos reproduced in the same way as cycads, another primitive group of plants. Sakugoro’s research surprised the scientific world. He later became an acclaimed botanist and painter.
One puzzling botanical question that is unlikely to be answered is how the Rhipsalis cactus came to Africa and Asia. All 2,000 recognized cactus species are native to the Americas, with the inexplicable exception of a handful of Rhipsalis species. Collectively referred to as wicker and mistletoe cacti, Rhipsalis are epiphytic plants that roost – non-parasitically – on tree branches from Florida to South America. Although they are interesting and moderately attractive in hanging baskets, several species of Rhipsalis have almost certainly not been introduced to Africa and Asia as ornamentals. The mystery persists.
An in-progress botanical puzzle identifies the myriad effects of chemicals called anthocyanins, which infuse new growth in many plants with red or bronze pigments. The chemicals also impart red, blue and purple hues to flowers, fruits, and vegetables and give brilliant fall colors to the foliage. When it comes to the tender new leaves, anthocyanins have been linked to their protection from intense sunlight and extreme temperatures, as well as deterring herbivorous creatures from munching on them. Research also highlights the role of these remarkable chemicals in combating pathogens. So far, however, there is no evidence that humans benefit from consuming brightly colored fruits and vegetables.
Charles Reynolds, a resident of Winter Haven, has an associate’s degree in horticulture and is a member of the Garden Writers Association of America. He can be contacted at [email protected]