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Transcript
What is a plant? Kingdom Plantae - technically plants are green photosynthetic organisms - Include 250,000 species - autotrophs - Produce organic sugar from CO2, water vapor and light - Base of many food chains/webs - Nonmotile - spend most of their lives anchored to one spot. - multicellular - Have a sex life – flowers possess male and female structures Three basic organs A. Roots Anchors a plant Absorbs minerals and water Store nutrients Three basic organs B. Stems Support the leaves and help orient the leaves to the sun. Conduct photosynthates from the leaves to other organs of the plant. Stems – transport water from the roots up to the leaves. Many different types of stems. Three basic organs C. Leaves – most are responsible for photosynthesis bracts spines What is a tree? A large, woody thing that produces shade Self-supporting, perennial woody stem To a horticulturalist a tree has a woody stem that is more than 20 ft (6 m) tall which branches at some distance above the ground. To botanists trees cover the sprawling small shrubs to the large giants that are over 100 m tall. A shrub has multiple stems and is less than 20 ft (6 m) tall. Horsechestnut tree Aesculus hippocastanum Valued as a landscape tree in Europe. It grows 50-70 feet high and has a 40 feet wide spread Not trees Lianas and other climbers Woody stems that die back to the ground each year like asparagus. Bananas – lack wood (the trunk is made from leaf stalks squeezed together. Bamboos – hardened grasses although they can reach 25 m tall and 25 cm thick. Asparagus shoot Virginia creeper -A woody vine/liana with five leaflets common bamboo (Bambusa vulgaris) golden stems marked with dark green longitudinal stripes. Wide range of plants that have a tree habit Conifers and their allies Redwoods, pines, spruces, hemlocks, firs, yews Cycads, Gnetales, Ginkgo Angiosperms – flowering plants Dicotyledons – main group of trees: oaks, maples, beeches, hickories, magnolias) Monocotyledons Palms (mostly tropical) Agavaceae (dragon trees) Liliaceae (aloes, yuccas) Xanthorrhoeaceae (grass trees that grow in Australia) Loblolly pine Pinus taeda L Leaves of Ginkgo When trees evolved Plants arose more than 400 million years ago (Silurian) First trees arose in the Devonian (390 million years ago) Coal producing swamps of the Carboniferous (360-290 million years ago are the result of lush forests – giant horsetails, clubmosses, and primitive conifers 250 million years ago there were cycads, Ginkgos, and monkey puzzle pines (fossils are found in the Arizona petrified forest). Pines evolved around 180 – 135 million years ago. Living fossils Trees that were once thought to be extinct but have been found in remote areas Ginkgo – silver apricot or maidenhair tree was rediscovered in Japan by Europeans in 1690. Dawn redwood (Metasequoia glyptostroboides) was found in China in 1945. Value of trees Sacred to people Oaks sacred to European Druids Baobabs to African tribes Monkey puzzles to the Pehuenche people of Chile Writing tablets were made from slivers of beech wood (Fagus sylvatica) Beech is the Anglo-Saxon word for book. Romans crowned athletes with branches from the bay laurel (Laurus nobilis) which was extended to scholars and poets. Roman students were designated as bachelors from the laurel berry (baccalaureus) leaving us with the bachelors degree (baccalaureate). Value of trees Timber – 2300 million m3/yr is consumed worldwide Paper making Housing Synthetic rubber Matchsticks (get about 1 million from an average Canadian aspen) Cloth made from bark by the Polynesians and Africans Rayon can be made from wood Keystone species – many other plants and animals depend on trees. Spices: nutmeg Myristica fragrans), cinnamon (Cinnamomum verum), cloves (Eugenia caryophyllus), coffee (Coffea arabica), tea (Camellia sinensis), and carob (Ceratonia siliqua) – from the old world Value of trees Papaya, avocado, cocoa, brazil nut – new world Olive oil and palm oil (used for margarine, candles, and soap) Artificial flavor of vanilla for cheap ice- cream is a chemical derivative of wood. Medicinal Extracts from Ginkgo are used to improve blood flow Quinine (Cinchoma spp.)’Jesuit’s bark from Peru is used to fight malaria. Brake linings in cars – made from lignin Trap and absorb pollutants Reduce stress and improve healing in urban areas Produce oxygen – a single mature beech tree can produce enough oxygen for 10 people per year. The shape of trees (growth habits) Conical outline or excurrent – conifers, sweet gum, yellow poplar Branches are produced in whorls around the main central axis Usually one whorl per year Deliquescent or decurrent – most deciduous hardwoods Leading shoot of a young tree gives way to a number of strong branches Columnar – single, unbranched trunk; leaves in cluster at top of trunk. Palms weeping fastigiate columnar The shape of trees (growth habits) Fastigiate – columnar growth with very short branches Dwarf – smaller than normal Weeping – branches lack hormones that maintain geotropy (e.g., weeping willow). The shape of trees (growth habits) Flat –topped, umbrella shaped Mediterranean stone pine (Pinus pinea) Resists drying winds – leaves hide behind each other out of the wind The shape of trees (growth habits) Trees grown in open areas have wide-spreading branches Trees grown in shade tend to be taller and narrower with fewer side branches to help acquire light. Leaf parts 1. leaf blade – portion of the leaf that is thin and flattened 2. petiole – stalk of a leaf may or may not be present 3. stipules – pair of appendages occur at base of leaf (occur in 25% of angiosperms) - May be attached to the petiole or stem - May form a ring around the stem - Colors: green, yellow, brown, red, or purple - Green stipules may be temporary or persistent photosynthetic structures - May be thin, and papery; hard and woody or spine-like. - Some plants loose their stipules after a leaf develops a scar may form. Leaf complexity Simple leaf – a leaf with a single blade Compound leaf - a leaf with more than one blade per petiole or leaf base Leaflet – one of the segments of a compound leaf Pinnately compound – a compound leaf; leaflets attached along a central axis Rachis – axis of a pinnately compound leaf A continuation of the petiole It is above the point of attachment of the lowermost leaflet equivalent to a midrib on a simple leaf has all leaflets attached to it Pinna – the primary division of a pinnately compound leaf Palmately compound – a compound leaf with leaflets radiating from a common point of attachment resembles fingers on a hand no rachis Leaf Arrangement 1. Opposite – two leaves attached at each node on opposite sides of a stem. 2. Alternate – only one leaf attached at each node. 3. Whorled – three or more leaves symmetrically distributed around the stem at same node Leaf Attachment Sessile – a leaf blade attached directly to a twig Leaf venation 1. Pinnate venation – one simple major vein 2. Palmate venation – more than one major vein ex: silver maple 3. Dichotomous venation - the veins branch in two over and over again - occur in ferns, Ginkgo, few angiosperms 4. Parallel venation - veins are in parallel arrangement - common to yucca, bananas, grasses, palms - These plants commonly possess a leaf sheath Stem features 1. Node – position on a stem where a leaf branch or aerial root grows 2. Internode – part of stem axis between two nodes 3. Axillary (side) bud – a bud born in the axis of a leaf 4. Terminal bud - located at the tip of the stem and it is the dominant bud - can cause all the lateral buds below to remain dormant FRUITS - Develop from the ovary of a flower and, often, other tissues that surround it. - Arise from fertilization - A seed container -Does not have to be sweet. - It protects developing seeds - May help disperse mature seeds Large diversity of fruit types Classified on the basis of the characteristics of the mature ovary Fruits can be fleshy or dry Identification - the determination of a specimen as being identical to or different from a previously known plant. - A previously known specimen is not always available and the unknown specimen may prove to be a new one. i.e.: Three specimens A, B, and C. - Specimen A is classified as Solanum nigrum. - Specimen B is similar to A and is considered to be S. nigrum. - Specimen C is dissimilar so further study is required How to determine an unknown 1. 2. 3. 4. 5. Consult a flora monograph in a library Look at herbarium specimens Look at garden specimens Ask an expert Use a taxonomic key –dichotomous keys are the most common. It consists of a series of two contrasting statements. - Each statement is a lead; the pair of leads constitutes a couplet - Select the best lead statement, then and then all couplets under that lead are sequentially checked for fit until identification is reached. Money Taxonomic Key 1. Is it made of metal? Yes ............................................... Go to 2 No ............................................... Go to 5 2. Is it a silver type color? Yes ............................................... Go to 3 No ............................................... Penny 3. Is the outer edge smooth? Yes ............................................... Nickel No ............................................... Go to 4 4. Is there an Eagle on the back? Yes ............................................... Quarter No ............................................... Dime 5. Do the corners have a number 1 in them? Yes ............................................... $1 Bill No ............................................... $2 Bill