Cycads are not unfamiliar to many people. As a beautiful ornamental tree species, it stands in landscaping and garden greening like a piece of living art, and has been widely cultivated in the north and south of the river. The tree is quaint in shape, with sturdy and hard branches, few branches, pinnate leaves often clustered at the top of the stem, young leaves are fist-rolled, mature leaves are inclined upward in a "V" shape, and the edges are rolled outwards. Its leaves are shaped like the tail feathers of the legendary phoenix, and the plant type is similar to a banana plant, so it is also known as "phoenix-tailed banana". According to legend, it needs a lot of iron in the process of growth. When it is on the verge of failure, if you apply iron powder or drive iron nails into its stem, it can make it revive and rejuvenate. This is the name of "cycad". . Another theory is that it is named because of its high density of wood, which sinks into water and is as heavy as iron, commonly known as "Iron Tree".
Cycads are dioecious plants, belonging to the gymnosperm. The female cone flower ("female flower") is botanically called megasporophyll, which is formed in the branch and top leaves of the female plant, and is spherical. 6 ovules, which develop into red seeds after pollination. The male flower ("male flower") is the microsporophyte ball on the male plant. It is a dense cone-shaped ball when it is just formed, which is equivalent to a "bud", and slowly elongates into a cylindrical shape. The inflorescence is shaped like a huge "pineapple fruit" and a golden "big corn cobs". Cycads generally bloom for about a week. Due to individual differences, the flowering time can last from mid-June to early July. Some plants will also appear "double flower" or even "multiple flower" phenomenon. The southern region generally takes more than 10 years to bloom, and the region north of the Yangtze River does not bloom almost all year round. Therefore, there are sayings like "The iron tree blooms, the dumb people speak", "the iron tree blooms and the horse grows its horns", "the iron tree blooms for a thousand years", and "the iron tree blooms once in a lifetime" to describe the occurrence of extremely rare new things.
Cycads are native to Fujian, Taiwan, and Guangdong. They are often cultivated in various places. They like warm and humid environments, are not resistant to cold, grow very slowly, and have long lifespans, which can reach 200 or even thousands of years. According to the observation of the staff of Shanghai Botanical Garden for many years, cycads can be planted in the open field for overwintering in Shanghai, but they need to be properly protected for overwintering when the temperature is -5° and below. The leaves with good growth can generally be maintained for 3 years or more. If the growth is poor or is damaged by frost or insects, they are often cut off to make them re-leaf to maintain a beautiful ornamental quality.
Cycads are one of the oldest species of extant seed plants on earth. They first appeared in the Paleozoic Permian era of dinosaurs about 280 million years ago. When the Quaternary glaciers came, the cycads distributed in the northern hemisphere experienced mass extinction. In my country, some cycads distributed in southern my country survived due to the blocking factors such as the Qinghai-Tibet Plateau and the Qinling Mountains. Existing cycads evolved from a few descendants left by many ancestral groups, so relict plants such as cycads are internationally known as "the giant panda of the plant kingdom". It has very important scientific value in the study of the occurrence and development of the flora of the Hengduan Mountains in China, the study of paleontology, paleoecology, paleogeology, paleogeography, and the origin and evolution of seed plants. In addition, the stems of cycads are rich in starch. During the difficult economic period of our country (1959-1962), farmers in cycad producing areas often excavated cycad pockets, peeled them, cut them into thin slices, ground them into powder and rinsed them in water to remove toxic components. After making starch, for consumption, commonly known as "sago". At the same time, the whole body of cycads can be used as medicine. Its roots, leaves, seeds, and trunks have different medicinal effects. The leaf extracts also have anti-cancer activities.
Cycads are relatively late in their flowering stage. Generally, it takes more than ten years from seed germination to adult plant flowering, and because of dioecious plants and often dioecious phenomenon, male cones often bloom about 1 week earlier than female cones, so The pollination effect is poor under natural conditions, and the seed setting rate is very low. Wild cycads are distributed in tropical and subtropical regions, with a narrow range, slow growth, weak population competitiveness, and indiscriminate excavation by human beings, resulting in serious ecological damage, resulting in a sharp decline in their numbers and urgent protection. The Flora of China records a total of 9 genera and about 110 species of cycads. There are about 23 species of cycads in my country, of which 11 are critically endangered (CR), 8 are endangered (EN), 2 are vulnerable (VU), and 2 are near threatened (NT). In 1999, all of them were included in the "List of National Key Protected Wild Plants" (the first batch), all of which are Class I protected plants. All cycads are listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora. At present, the cycads introduced and preserved in ex situ in Shanghai Botanical Garden include cycads and cycads, and cycads are in full bloom.