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Plant Structure and Taxonomy Unit 15 Agriscience When early man started the practice of growing plants for food it allowed Them to stay in one place and produce food there. The beginning of Civilization started here. With out the equation of life, photosynthesis, we would have neither food Or oxygen. Photosynthesis uses the sun energy to convert non-organic Material into organic sugars.
The Plant Roots- May be the largest part of the plants, absorbs water and minerals Adventitious –appear where roots are not expected to appear Tap – Thick root that grows straight down used for food storage Fibrous – Thin hair like structures helps to stabilize soils. Structure – parts of the root Root Cap – penetrates the soil and is the area of cell division and Elongation. Xylem carries water and minerals up Phloem carries food down Root hairs – Area of cell maturation and absorption of minerals and Water.
Stems Support leaves, flowers, and fruit. Woody – Tough and winter hardy Herbaceous – Succulent full of water or sap Modified stems – special stems Bulbs – short stems surrounded by scales Corms – fleshy stems stem parts grows up and root part goes down Rhizomes – thick stems that run below ground and rise up to form New plants Tubers – thick underground stems for food storage
Stem Parts Dicots have vascular bundles where xylem and phloem are together in the Monocots have the xylem and phloem separated into specialized areas of Node – swollen area where leaves or buds will grow Internode – area in between nodes. Axillary buds – appear in the angle above a leaf or flower. Leaf or branch formation Lenticels – pores in the stem Terminal bud – tip of a stem. If the terminal bud is vegetative a Stem or vine will grow. If the terminal bud is flowering or floral The stem will not grow but produce a flower.
Leaves Produce food - phototropism Margins – edges of the leaf (smooth, serrate) Identify species Shape and form – (ovate, spatulate) used for identification Types of leaves – Simple leaves have one blade and one stem Compound leaves have many blades attached to one stem a blade is the wide part of the leaf while the petiole is the stem of the leaf. Structure Cuticle – outer coating of a leaf. Can be waxy Epidermis – surface on the upper and lower surface of the leaf Palisade cells – elongated, vertical cells for food production and strength. Spongy layer – also contain chloroplasts Chloroplasts – contain chlorophyll for photosynthesis Mesophyll – the palisades and spongy tissue collectively Xylem – minerals and water up Phloem – food down Stoma – openings in the leaves Guard Cells – control the open and closing of the stoma
Flowers Production of seeds Bract – modified leaf often mistaken for a flower (poinsettia) Stamen – male part of the flower made up of the filament (stalk) and the anther (produces the pollen) Pistil – female part of the flower made up of the stigma (catches the pollen), the style (neck), and the ovary (which contains the ovules or eggs) Perfect flowers contain both male and female parts, while imperfect flowers only have One or the other. Corolla – the colored part of the flower (petals) Sepals – the protective covering for the immature flower Calyx – all the sepals collectively Fruit – a pistil that enlarges and produces flesh that covers the seed (aids in seed dispersal Vegetable – any plant that is grown for an edible part. Nut – a specialized type of fruit
Plant Taxonomy The classification of plants that is based on similarities and differences. The Latin language is used because it is a “dead” language. It is Not used and does not change. This system was developed by Carl Linnaeus A shorter version is called the binomial system in which only the Genus and Species of a plant is used to identify it. Varieties are a sub group of species such as Ladak alfalfa. (Alfalfa Is Metacago Sativa.