Open Seeded Plants (Gymnosperms)
Gymnosperms mean gym = naked and sperm = plants that produce seeds. So, Gymnosperms are plants that have open seeds.
Gymnosperms group plants
Gymnosperms group plants have characteristics, namely:
- Seed beans are not protected by fruit leaves.
- Rooted riding.
- Generally a tree.
- It has true roots, stems, and leaves.
Biologists classify Gymnosperms into several divisions
- Cycadales division Cycadophyta, for example, hajj fern (Cycas rumphii)
- Ginkgoales division Ginkgophyta, for example, Ginkgo biloba
- Coniferales division Pinophyta, examples of pine, fir, and resin
- Gnetales division Gnetophyta, for example, Gnetum gnemon
Reproductive Tools In Gymnospermae
All Gymnosperms are heterotrophs, meaning they have two kinds of spores, namely microspores and megaspore. Microspores or pollen produce male gametophytes, while a single megaspore produces female gametophytes, and in these gametophytes, Oregonia is formed. The two kinds of spores produced in sporangia are contained in sporophylls arranged in a spiral in the strobili axis.
Sporophytes that turn out microsporophylls with microsporangia are referred to as male strobiles (staminate cones), whereas people who turn out megasprofils with ovules (together with aspadians) ar referred to as feminine aspirates (pistillate cones).
The characteristics of the Pinaceae family :
- Woody tree, conus-shaped strobilus.
- Needle shape & flocking or similar scales; the leaves and scales are arranged in a spiral; loose scales and branches
- Each scale with two (2) winged seeds.
- Male and female strobilus in one tree; male strobilus is smaller than female strobilus (woody), located axillary.
- Pollination & dispersal of seeds with the help of wind.
- Pollen with two air bubbles.
- Cotyledon a lot.
Covered seed plants (Angiosperms)
Closed seed plants have more species than open seed plants. The angiosperms group has more species because the gymnosperms plant only grows under certain environmental conditions, while angiosperms can grow in various natural conditions and mostly single 1 so that it allows for crossing to produce new variants in 1 species.
Closed seed plants (Angiosperms) are derived from the words angio = flower and semen = seed plants. This plant has a real flower consisting of petals, flower petals, pistils, and stamens.
In general, closed seed plants have the same characteristics as open seed plants. The uniqueness of closed seed plants lies in its seeds which are composed of institutional pieces (cotyledon). Institution pieces in closed seed plants form two groups of plants, namely single seed plants (Monocotyledonae) and double seeded plants (Dicotyledonae).
Dicotyledonae and monocotyledonous plants
Two-seeded seeds, rooted riding, cambium stems so enlarged branched, pinned leaves/fingers and flowers both crowns and petals multiples 4 or 5, the type of regular circular carrier with open collateral type (Xylem and phloem separated cambium) examples: mango, guava, rambutan, etc.
Dicotiledonae Characteristics :
- Have 2 cotyledons (leaf institutions)
- Cambium and branched rods
- Layout of xylem and phloem regularly
- Crown of flowers multiples of 2, 4,5
Having one-seeded seeds, rooted in fibers, stems from the base to the ends almost the same size. Generally unbranched. Roots and stems not cambium. For example Oryza sativa (rice), Zea mays (corn), Musa paradisiaca (pi sang), Cocos nucifera (coconut).
Monocotile Characteristics :
- Have 1 cotyledon
- The stem is not cambium and straight
- Location xylem and phloem scattered
- Fiber fibers
- Crown of flowers multiples 3
The seeds contain embryos from sporophytes, food reserves, protective skin. Embryos in the seeds are dormant (‘sleeping’ or inactive ) so that they can survive for long periods without the addition of water or food. when favorable conditions the embryo begins to grow or it is said the seeds begin to germinate.
- a seed containing an embryo wrapped in a seed coat called testa
- in seeds stored food reserves or endosperm, which are used by plants to grow and develop
- Seeds are formed from mature ovules that have been fertilized
The parts of seeds
- the first root called a radicle
- one or two sheets of embryo leaf called cotyledon
- the first leaf called a plumula which will branch out to form branches
- The stem located at the bottom of the cotyledon is called hypocotyl
- the stem located at the top of the cotyledon is called epicotyl
Seed plant characteristics
- experiencing descent in his life cycle
- multiply by using seeds
- has a transport network (fascist) to circulate water and food.
Angiosperms and Gymnosperms are the two most developed subdivisions of kingdom Plantae. Some characteristics distinguish these two subdivisions. Especially on the seeds.
As the name implies, Gymnosperms seeds are not covered by fruit flesh so they are often called bare seeds (gymnos = naked, and sperm = seeds). Conversely, Angiosperms seeds are covered by a kind of fruit flesh (Angieon = bottle, and sperm = seed).
The name Angiosperms refers to female reproductive organs that resemble bottles.
Difference between Angiosperms Reproduction and Gymnosperms
Reproduction in Angiosperms
The main features of angiosperms are as follows:
- seed ovens are covered by sporophylls in the form of carpels or fruit flesh and as a whole form ovaries or ovaries,
- there are clear pistil which is divided into three parts, namely: pistil head, pistil stems, and ovaries,
- have a true flower consisting of: flower jewelry, stamens, and pistils, d. after pollination, fertilization occurs, the ovule will become a seed, the wall of the ovule will become the flesh of the fruit.
The formation of female gametophyte comes from the cleavage of the primary organ’s nucleus in the ovule.
The process of formation is as follows: primary organ nuclei divide by three times in a row so that eight nuclei are formed, three nuclei in the microfilm region consisting of one egg and two egg cells enclosing the cells, called synergid cells.
Three nuclei in the chalaza region are called antipodes, and the two nuclei moving to the center of the bladder institution merge to form the bladder core of the secondary institution. So female gametophyte consists of eggs ( n), synergid cells (n) and the nucleus of secondary institutions (2n).
Male gametophytes are formed in the pollen bags. During Gametogenesis the pollen core divides to produce a vegetative core and a generative core, which are not as large. Vegetative cells are bigger than generative cells. The generative cell nucleus divides by mitosis and produces 2 sperm cells.
The fertilization process starts with the process of invasion. The difference between pollination and fertilization is relatively short. When pollen falls on the pistil’s head, a pollen reed is immediately formed.
At the tip of the pollen reed, there is a vegetative nucleus acting as a guide for the two sperm nuclei. Furthermore, the pollen reeds continue to grow to reach the ovule. In the ovary nucleus, the sperm I (n) fertilizes the egg (n) to form a zygote (2n) and the sperm nucleus II (n) fertilizes the nucleus of the secondary institution to form endosperm (3n). This fertilization event is called double fertilization.
Gymnosperms don’t yet have real flowers. Reproductive organs are called conuses or cones protected by scales. There are 2 types of conifers namely female cones and male cones. Male conifers have several microsporophylls.
Each microsporophyll has two microsporangia in which microspores stem cells are formed. Microspore stem cells will undergo meiosis produces four haploid microspores. Female conifers consist of a central axis that is attached by scales. Each scale has two ovules (ovule).
Each ovule is coated by an integument that is united with megasporangium. In megasporangium, there is a megaspore stem cell that will undergo meiosis to produce four megaspores. Three of the megaspore will reduce themselves so that only one functional megaspore will remain.
The pollination and fertilization process occurs as follows: Pollen begins to germinate and form a pollen tube and enters the megasporangium tissue. Generative cells divide into stem cells and body cells.
Body cells divide to form male gametes or sperm. The pollen tube will penetrate the neck cells of the archegonium and release its contents into the egg. One of the sperm cells will unite with the egg and all the rest of the male gametophyte nucleus will be reduced.
Difference between Gymnosperms and Angiosperms
- In Gymnosperms the reproductive organs in the form of strobilus, between male and female strobilus are separated while in Angiosperms their reproductive organs are flowers with stamens and pistils. yarn pollen and pistil there are contained in a single flower.
- Gymnosperms the seeds will not be protected by fruit leaves. Angiosperms the seeds will be protected by fruit leaves.
- Gymnosperms are single fertilization models. Angiosperms Model is double fertilization.