Pteridophyte is the earliest vascular plant that landed, and it is still an important part of the primary productivity of the ecosystem. On the one hand, they can affect the occurrence and development of forest communities by transforming the ecological environment. On the other hand, due to their sensitivity to changes in ecological factors, their composition diversity and adaptability to the environment are constantly changing with the occurrence and development of forest communities. There are more than five families, including Dryopteridaceae, Dryopteridaceae, Pterisdaceae, Selaginellaceae and Dryopteridaceae. Athyridaceae, Athyridaceae, Ranidae. Pteridophytes in Dapeng Peninsula have typical floristic characteristics of south subtropical zone. According to the different growth substrates, the pteridophytes in Dapeng Peninsula can be divided into four ecological types: native, lithophytic, aquatic and epiphytic, among which the native type is the main one. [Abstract]

Based on the investigation of pteridophyte quadrat in Dapeng Peninsula, Shenzhen, the species composition and floristic characteristics of pteridophyte in quadrat, as well as the abundance, frequency, population importance, growth type, leaf characteristics, community appearance and seasonal community characteristics of pteridophyte were preliminarily analyzed. The results show that there are pteridophytes 105 species in this area, belonging to 35 families and 65 genera.

At the same time, the origin, life history, morphology and medicinal use of pteridophytes are introduced.

[Keywords:]

Pteridophytes and Vegetation in Dapeng Peninsula

[Text]

Botanists have different views on the origin of pteridophytes. Most people think that ancient pteridophytes originated from green algae, mainly because they all have similar photosynthetic pigments and storage substances-starch, alternate generations, flagellated swimming sperm and multicellular sexual reproductive organs. As for the statement that pteridophytes originated from bryophytes, there is insufficient evidence to explain the great difference in their life history.

Pteridophytes are plants with vascular bundles and reproduce with spores. Terrestrial or epiphytic, rarely aquatic. Most of them are perennial herbs, but many of them were tall woody plants in ancient times. Sporophyte consists of roots, stems and leaves. The gametophyte degenerates into a very small prothallus with a false root and lives independently. The stems are mostly rhizomes, and only a few are erect or prostrate. Rhizomes are often covered with scales or scales, and the internal structure has primary steles, such as pine trees.

Pteridium aquilinum (psi1otum); Woven stele, such as Lycopodium, tubular stele and reticulate stele, such as Phyllostachys pubescens.

There are two kinds of leaves: small leaves and big leaves. The leaves are small and leaflike, and the stems are more developed than the leaves, such as Lycopodium and Equisetum, and the leaves are large, and the leaves are single or divided into pinnate, such as Pteris, and the veins are separated or connected, and the separator has bifurcated, fan-shaped or pinnate veins; Connectors are usually interwoven into various grids. In some species, some leaves are completely covered by cryptosporangium, which are called spore leaves or fertile leaves, while others

Leaves without sporangia are called vegetative leaves or sterile leaves.

Roots are usually adventitious and form fibrous roots; Most of them are rhizomes, crawling or walking sideways. A few of them have stems on the ground, standing upright as trees, such as spinulosa spinulosa. The stems of ferns are usually covered with scales or hairs. Scales are membranous and varied in shape, and there are often thick or thin sieve holes on scales. Hairiness includes unicellular hair, glandular hair, nodular hair and stellate hair. Most leaves of ferns come from rhizomes.

It grows in the world, clustered, near or far, and is mostly fist-shaped when it is young, which is the original character. According to the source and morphological characteristics of leaves, they can be divided into lobules and large leaves. Microveinlets have no leaf gaps and petioles, only 1 unbranched veinlets, such as leaves of plants such as Lycopodiaceae, Selaginellaceae and Equisetaceae. Big leaves have petioles, gaps and multi-branched veins, which is evolution.

Types of leaves. Such as the leaves of real ferns. There are two kinds of big leaves: simple leaves and compound leaves.

After the spores of ferns mature, they are scattered in a suitable environment and germinate into tiny green leaflike bodies with different shapes, which are called prothallus. This is the gametophyte of ferns. The gametophytes of pteridophytes are mostly born in humid places, with dorsal nature and can live independently. When the gametophyte matures, most of them produce sexual reproductive organs on the ventral side of the same gametophyte, that is, spherical spermatozoa and bottle-shaped cervical eggs.

Equipment. There are flagellated sperm in the spermatozoon and egg cells in the archegonium. After the sperm egg matures, the sperm leaves the sperm organ and enters the archegonium with water as the medium to combine with the egg. A fertilized egg develops into an embryo and from an embryo into a sporophyte, which is a common fern.

Ferns have obvious generation alternation, from haploid spores to gametophytes to produce sperm and eggs. This stage is haploid gametophyte generation (also called sexual generation), from fertilized egg to sporangium produced on the sporophyte before meiosis, and this stage is diploid sporophyte generation (also called asexual generation). These two generations regularly complete their life history alternately. There are two biggest differences between ferns and bryophytes in life history. One is that sporophytes and gametophytes can live independently. First, the sporophyte is developed and the gametophyte is weak, so the life history of ferns is the alternation of different generations dominated by sporophytes.

Classification of pteridophytes

There are about 12000 species of modern pteridophytes, most of which are herbs, which are widely distributed all over the world and grow in humid and warm environments. There are about 2,600 species in China. There are different opinions about its classification system. As a natural group, it is usually classified into pteridophyta, but it is also divided into four phyla: gymnospora, pteridophyta, arthropoda and pteridophyta. Pteridophytes were once divided into 4 classes or 5 classes. This book adopts the internationally accepted Qin Renchang 1978 system, and divides it into five subfamilies: Gymnodinium, Lycophyceae, Isodinophyta, Sphenophytina and Filamentophyta. Among them, the first four subfamilies are Pteris microphylla, also known as Pteridophyta, which are some primitive and ancient pteridophytes.

Historically, it once dominated the earth, but there are few existing species. Pteridium aquilinum is a kind of fern with big leaves, an evolutionary type and an extremely prosperous fern in modern times. Medicinal components of pteridophytes

Alkaloids are widely found in Pteris microphylla, such as lycopodine, cudgel alkaloid, lycopodine and so on. Jinpacaine has a strong analgesic effect.

Phenolic compounds, dihydric phenols and their derivatives such as caffeic acid, ferulic acid and chlorogenic acid are common in Pteris macrophylla. These components have antibacterial, dysentery-relieving, hemostatic and leukocyte-increasing effects. Caffeic acid also has antitussive and expectorant effects. Polyphenols, especially phloroglucinol derivatives, exist in most species of Dryopteris, such as filicicacids and dryocrassin. These compounds have strong anthelmintic effect, but they are very toxic.

Flavonoids exist widely, such as isoquercitrin and kaempferol. Selaginella and Cynanchum auriculatum contain apigenin and luteolin, while Quercus variabilis contains hesperidin and naringin. Mountain rat Contains many kaempferol derivatives. β-sitosterol, mangiferin, isomangiferin, etc. Isolated from different plants of the genus Thermopsis.

Steroids and triterpenoids contain lycoclavinin and lycoclavanol in Lycopodium, and Huperzia serrata contains tohogenol and tohogininol. Insect ecdysone exists in Astragalus membranaceus, Dryopteris Dryopteris and Polypodiaceae, which can promote the synthesis of protein, eliminate cholesterol and reduce blood.

Activities such as blood lipid and inhibition of blood sugar rise.

Pteridophytes contain tannins, and spores of Lycopodium and Lygodium japonicum also contain a lot of fat. The underground part of Dryopteris Dryopteris contains trace volatile oil. The leaves of Phomophilum morifolium. )Kitag。 Contains coumarin. In addition, there are many trace elements, silicon and silicic acid, some of which have different physiological activities, and these components deserve further study. Key to pteridophytes

1. Plants have no true roots, only pseudoroots, and 2~3 sporangia form aggregates.

1. Plants have true roots and do not form aggregates. Sporangiums are solitary or aggregated sporangia.

2. The plant has obvious nodes and internodes, the leaves degenerate into scales, and photosynthesis cannot be carried out, and the spores have elastic filaments. ..........................................................................................................................................

2. Unlike the above, plants have green leaves, lobules and big leaves, which can be used for photosynthesis, and spores are inelastic.

3. There is no boxing phenomenon in lobules and young leaves.

4. The stems are multi-branched, with lobules and scales. Spore leaves gather at the top of branches to form ear of spore leaves. Spores are homomorphic or heteromorphic, and sperm has two flagella. .......................................................................................................................

4. Stems are as thick as tubers, leaves are as long as leek leaves, spores do not form spikes, spores are abnormal, and sperm have multiple flagella.

3. The leaves are large, and the young leaves have the phenomenon of fist bending, and sporangia gather on the back or edge of spore leaves to form sporangia groups. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

[reference]

Study on pteridophyte flora and its ecological characteristics in Dapeng Peninsula, Shenzhen in 2004

Research progress on the relationship between the origin and phylogeny of pteridophytes in Li Chunxiang

Zeng Xianfeng Journal of Hanshan Teachers College-Newly Recorded Plants in East Guangdong, 2004.

Zeng Hanyuan's biological bulletin on the research progress of key protected pteridophytes in China in 2002

Study on Medicinal Pteridophytes in Liao Fulin Yinnashan Nature Reserve, Journal of jiaying university, Guangdong (Natural Science Edition) 2004.