LESSON 10 PLANTS. Pteridophytes.(Cormophytes) Ferns: have woody vascular conduicts.

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1 LESSON 10 PLANTS The plant kingdom. Plants originated as part of a group of green algae approximately 500 million years ago. They were the first living beings to colonize the Earth. Plants are multi-cellular(eucariotyc)living beings that create their own organic material through the process known as photosynthesis, the reason they are known as autotrophs. Bryiphytes. These plants, then, are incapable of remaining erect so they tend to be small and develop close to the ground and are characterized by living in humid, shady environments. These plants don't have root, stem and leaves. (Thallophytes) Liverworts: non-vascular conduicts, the cells absorb water and substances that they need directly from the ground and they pass from cell to cell through diffusion. Pteridophytes.(Cormophytes) Ferns: have woody vascular conduicts. They have roots, stems and leaves but lack flowers and seeds. Ferns live in humid and shady areas. In general, these plants do not grow taller than 1.5m, although in some tropical areas some specimens can reach several meters. The classification of plants. a) Plants without flowers.(cryptogams) Bryiphytes.(Thallophytes) Liverworts: non-vascular Mosses: don't have woody vascular conduicts. Pteridophytes.(Cormophytes) Ferns: have woody vascular conduicts. b) Flowering plantas.(phanerogams) Spermatophytes. Angiosperms: with ovary and fruit. Gymnosperms: without fruit. Mosses: don't have woody vascular conduicts. And have three parts: axis (similar to a stem), phylloides (similar to leaves) and rhizoids (similar to roots).

2 b) Flowering plantas.(phanerogams).plants with flowers Spermatophytes. Plants with flowers, or Spermophytes, reproduce though seeds that form a special organism: the flower. Angiosperms. Angiosperms are the newest type of plants. The Flower The flower is the reproductive organ of angiosperms. In flowers there are four different types of leaves: sepals, petals, carpels and stamens. isolated in the stem, but formed groups that are called inflorescences. Fruit and Seeds. Angiosperms are characterized as such because they produce fruit, bodies from the ovary of the flower that can contain one or many seeds. Gymnosperms. Gynmosperms appeared before angiosperms, about 300 million years ago. Their most representative characteristics are: a) All are woody plants. b) In a large number of species, the leaves are narrow, in the form of a needle (like pines) or a flake (like cypresses), and tend to be perennial. c) The flowers are always unisexual: there are male flowers and female flowers. d) They do not have fruit but rather the seed appears bare. Flowers that have all four types of leaves are called complete.some flowers do not have calyx or corolla and it is then said that they are naked. When the same flower presents stamen and carpels, the flower is considered a hermaphrodite. Those that only have stamen are male flowers and those that only possess carpels are female. In general, flowers are not Fruits are characterized as fleshy (like a tomato or peach), when the part surrounding the seed is a juicy mass and dry (like a sunflower seed or nuts) if the seed is surrounded by a hardened structure. Fruit makes possible the dispersion of the seeds. Pine Cypress Conifers Inside of the gymnosperms, the largest and best known group is the conifers, which includes pines and firs.

3 The flowers of the conifers lack petal and sepals and are unisexual. The female inflorescences are called pine cones. Conifers do not form fruit. Functions of the root Roots have two principle functions: a) Fix the plant to the ground. b) Absorb water through the absorbent hairs and take in minerals that constitute the raw sap. Types of roots There are three types of roots. 1.Tap Root : a) These show a principle root, from which grow various lateral axis or secondary roots. It is characteristic of bean. b) This is formed by a very thick principle root which accumulates reserve substances. The stem. The general structure of spermatophytes. The structure of all spermatophyte plants present three basic parts: roots, stems and leaves. The root. The root is the part of the plant that grows in the opposite direction of the stem and, in general, is underground. Parts of the root: This is the case in the root of a carrot. 2. Fibrous root: In these there is no distinction between the principle root and the secondary roots, they have the same thickness and localize it as a tuft of hair, like the root of an onion. 3. Adventitious root: ooriginated from stem, branches or leaves The stem is the axis of the plant, thanks to which it maintains rigidness. It also serves to support the leaves and flowers and connects the leaves with the roots. Parts of the stem: In the principle axis nodes are distinguished which connect the leaves and branches to it.

4 The space between two nodes is called the internode. Buds are the growth on the stem that allow this development. They can be terminal, responsible for the growth in length of the stem, and auxiliary, when branches grow. a) Duration: They are annuals if they grow for one year, or perennials if they grow for two or more years. b) Consistency: They are non-woody if they are soft and woody if they are tough and not green. c) Distance from the ground. The aerials are the most common; normally they are erect like that of a pine tree or a palm tree, but they can also be a climber like in the case of the stem of ivy. The aquatics develop close to water, for example, those seen in water lilies. The underground grow underground and can be thick because they accumulate reserve substances. Onion. Leaves. Leaves are expansions in the form of a plate, generally green in color, that grow from the trunk or the stems of a plant. Parts of the leaf: In the drawing of the leaf you can see: a) The blade, or flat part of the leaf. b) The upper face of the leaf, called the top part, and the lower face, underside or bottom, which is crossed by veins, that are the vessels where raw sap and sap are transported. c) The petiole, the corner where the leaf joins the stem. The stem is the axis of the plant that supports the leaves and the flowers and also provides transportation of the sap between the leaves and the root. Types of stems: Stems can be classified with the following three characteristics: Functions: photosynthesis is done in the leaves. At the same time, the plants regulate the quantity of water that reaches the whole plant through transpiration, the mechanism of elimination of water in the form of vapor. This loss of water is produced during the day through the stomas, holes that are found on the underside of the leaves. Types of leaves: The same as with stems, classification of leaves can be made using distinct criteria:

5 a) Type of venation. If the leaves have only one central vein, like those of a pine, it is said that they are single; if they present a principle vein that is separate from several secondary veins, the nervation is pinnate; if at the same point of the principle vein there are other secondary veins that are of the same importance it is said that the nervation is webbed; if the top side has parallel veins running from one end of the leaf to the other, the nervation is parallel. b) Shape of the blade. Leaves can be simple when the blade is complete, that is to say that it is in one piece, and compound, if the blade is divided into pieces called leaflets. Simple leaves can have the form of a needle, lanceolate (lance), oval, heart-shaped, elliptical, sagittate (like the point of an arrow) etc. c) The margin of the blade: entire, serrate, dentate, lobed, sinuate, cleft, etc SHAPE VENATION MARGIN