........................................... PLANTEA KINGDOM II. The Gymnosperm

Introduction. This chapter covers the topic of plants with flowers in general and, in more details, the Gymnosperms. In the first place it is needed to note that not all flowers are very showy, but there are flowers as those of pine or wheat, which are very inconspicuous. That is, there are flowering plants, such as pine or wheat, which at first glance does not look to be one. The reason why there are plants with and without showy flowers is related to the strategy followed by the plant to disperse pollen produced by its flowers. It it is done with use of insects or hummingbirds, it is necessary that flower produces a food for them (nectar) and has a very showy petals to be easily seen. However, if pollen dispersal or pollination is done through the wind, there is no need for plant to invest energy to produce nectar or make big and colorful petals.

Other issue that needs to be explained, is that pineapples or pine cones, despite containing seeds inside them, are not a type of fruit, such as an apple, peach or bean. In pineapples, the seeds are not only inside. The proof of this is the fact, that when pineapple ripes and opens the seeds fall by themselves. In fruits the seeds do not fall, but stay inside. The function of previously mentioned fruits is to offer food in order attract animals which eat them and, because seeds resist theirs digestive juices, are excreted with feces and by that, dispersed. Reflecting on all this, we can see that it is almost unbelievable to understand how it was possible to establish these sophisticated survival strategies among species as different as plants and animals.

Activities to do. Read the explanations on the general characteristics and classification of plants and perform Multiple Choice Test 14.1 and Relate Pictures with names 14.1 and 14.2. Then read the text on the Gymnosperms and perform Multiple Choice Test 14.2, Relate the pictures with names 14.3 and 14.4 and Crossword 14.

1. The Plantea Kingdom.
The plants can be classified into two groups based on whether they have or do not have flowers. These are:

• Cryptogams. Are the plants that do not have flowers and, therefore, do not produce pollen neither produce seed. It covers the moses and ferns.

Spermatophytes or Phanerogams. Are the plants with flowers and, therefore, they do produce pollen and then seeds. It covers Angiosperms and Gymnosperms.

• Gymnosperms. Are those plants that produce seeds but not fruits. As a result their seeds are not enclosed in fruits. For example pine.

• Angiosperms. Are those plants that produce seeds and fruits which ebrace and protect the seeds. For example almonds.

2 . The structure of Spermatophytes. Such as ferns, they have conductive tissue and and other types of tissues. Because of this, in their body three organs can be distinguished, which are: the root, stem and leaves. Having these three organs means having a cormophytic structure. Moreover, they have flowers to reproduce. In this, they differ from mosses and ferns.

Root. It is the underground organ which sets plant to the ground and absorb water and minerals through the root hair, called xylem sap.

Stem. It is the organ that holds the leaves, that gives them the xylem sap from the ground and distributes the organic matter, which is manufactured by them, called pholem sap , throughout the whole plant.

Leaf. It is a layer structure of color green, because of the presence of chlorophyll in the chloroplast of its cells. It has three parts: the limb or laminated part with veins, the petiole which is the part that connects the blade to the stem, and pod, which is the widest area of the petiole which embraces the stem. The upper part of limb is called beam and the lower - underside. The leaf is the body responsible for photosynthesis, which means to synthesize organic matter from water and minerals absorbed by the roots and carbon dioxide absorbed through limb pores called stomata. Through them the oxygen, which was produced during photosynthesis, leaves.

Flower. It is the organ that allows the sexual reproduction of a plant without the need for water for the male gametes to move (as happens with mosses and ferns), because they move through the air inside the pollen grains. The flower produces grains of pollen and ovum.

The grain of pollen contains the male gametophyte and protects it from drying, which allows it to spread through the air.

The ovum contains the female gametophyte and keeps it moist inside the flower awaiting the male gametes which contains pollen.

Multiple Choice Test
Relate pictures with names
Relate pictures with names

3. The Gymnosperms
. Are the plants with flowers but without fruits, so their seeds are not enclosed in fruits but exposed. The most abundant group of gymnosperms are the Conifers or plants with cones, structures that are commonly known as the pineapples. The Conifers are trees (there is a the main stem and then branches) or bushes (not a single main stem). The most abundant in our country are the pines. When looking at a ripe pineapple it can be seen that their seeds, pine nuts, are not inside the cone but have contact with the outside. Other conifers are the cypress, the fir and the cedar.

4 . The features of the pines.

1. They have needle-shaped leaves (acicular) and a thick cuticle with waferproof surface that helps prevent water loss. The acicular shape makes it more difficult for them to dry out than the flat shape. It is therefore an adaptation to dry climates (both hot and cold). It also facilitates the sliding of snow and makes it more difficult for the leaf to freeze which is why high mountain pines do not need to lose the leaves during the winter (evergreen leaves) and can take light all year.

2. The secrete the resin for prevent the attack of wood-eating insects.

3. They have two types of flowers: female flowers and male flowers. The flowers are very small and have very simple structure because they have no petals.

The female flower is reduced to a single scale, which creates two ovums in the inside. These little flowers or scales are grouped forming a set called female inflorescence, which is a small green pulpous pineapple, about a centimeter in length, which is placed at the end of the upper branches.

The male flower has a lobe shape and consists of numerous yellow scales which correspond to the stamens of flowers in the form of scales that produce large amounts of pollen grains. Male flowers are grouped forming a set called male inflorescence, which have a shape of spike and is located at the lower end of the branches.

4. Ciclo biológico. Durante la primavera se forman las flores masculinas y sus estambres liberan los granos de polen. Estos son transportados por el aire hasta los óvulos de las inflorescencias femeninas. Tras la fecundación, a lo largo de unos dos o tres años, la inflorescencia femenina se va transformando en una piña que al abrirse deja caer sus semillas, los piñones. La disposición de las inflorescencias masculinas dificulta la autofecundación, lo cual disminuiría la capacidad de supervivencia de la especie.
Multiple Choice Test
Relate pictures with names
Relate pictures with names
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