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Download Investigation 19- A survey of plant kingdom
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6.2 CLASSIFICATION OF PLANTS Time required: 2 periods Name:_____________ Introduction: All plants are placed in the Kingdom Plantae. Plants are then divided in two Divisions: Vascular and Non-Vascular. Vascular plants known as Tracheophyta have vascular bundles consisting of xylem vessels and phloem vessels. Xylem vessels carry water and minerals and phloem vessels carry nutrients. Non-vascular plants do not have vascular bundles. Divisions are divided into classes, and they, in turn, into orders, families, genera and species. The major divisions of plant kingdom are: bryophyta (mosses and liverworts), pteridophyta (seedless plants), Spermatophyta (produce by seeds) coniferophyta (conifers), angiosperms (flowering plants) and gymnosperms (non-flowering plants). Angiosperms are again divided into monocotyledons (have one seed leaf) and dicotyledons (have two seed leaves). Fungi are plants, which have no chlorophyll and are placed in a separate kingdom Fungi kingdom. Algae, like plants, are photosynthetic and manufacture their own carbohydrates, but they are classified in the kingdom protista. Algae are photosynthetic plant like organisms which are placed in kingdom protista. Fungi are classified in the kingdom fungi. Fungi, unlike plants and algae, cannot manufacture their own food by photosynthesis. They need an external source of nutrients. Lichens are also classified in the kingdom fungi, but they are actually mutually beneficial associations between certain fungi and photosynthetic algae or bacteria. The alga produces sugars by photosynthesis and the fungus creates a thallus or body that houses both organisms. This collaboration enables lichens to colonise harsh, exposed habitats where few other organisms can survive. Pre-lab activity: Get yourself familiar with the characteristics of different types of plants prior to the lab and define the key terms. Key terms: Tracheophyta, bryophyta, pteridophyta, spermatophyta, angiosperm, gymnosperm, vascular plants and non vascular plants Objectives: To classify plants into different divisions and classes by observing their external characteristics and mode of reproduction. Apparatus and materials: Moss with spores and rhizoids Pine with leaves and cones Magnifying glass Liverwort with spores Lichen Geranium plants with leaves and flowers Lab coat Lily plant with leaves and flowers Disposable gloves Fern with roots and leaves with spores Bean plant with roots and seeds Magnifying glass Corn plant with roots and seeds Note: If live or preserved specimens (which are preferable) are not available, use clear photographs or diagrams. 1 Plant kingdom Bryophyta No vascular bundles Bryopsida e.g. moss Hepataopsod a e.g. liverwort Traceophyta Have vascular bundles Arthoceropsi da Pteridophyta No seeds Spermatophyta Have seeds e.g. hornwort Pteridopsida e.g fern Psilopsida Sphenopsida e.g whisk fern e.g horse tail Gymnosperms Have no flowers Penopsida e.g Pine tree Psycadopsid a e.g Cycad Angiosperms Have flowers Gingkopsid a Gnetopdida Monocot s e.g ginkgo e.g gnetophyte e.g wheat plant Figure 1- Plant classification flow chart Dicots e.g flowering plant 2 Table 1- Distinguishing features of plants in different divisions, classes and subclasses Phylum Division Non vascular plants Have no vascular bundles Bryophyta Class and subclass Class- Bryopsida-Mosses Class- Hepatopsida-Liverworts Class-Arthoceropsida-hornworts Pteridophyta Seedless plants Class-Pteridopsida -Ferns Class- Psilopsida – whisk ferns Class- Sphenopsida - Horse tails Class- Gymnospermae Nonflowering plants Subclass – Pinopsida- conifers Tracheophyta Vascular plants Have vascular bundles Subclass-Cycadopsida- cycads Spermatophyta Seeded plants Subclass-Ginkgopsida- ginkgo Subclass-Gnetopsida- Gneto phytes Distinguishing features Bryophytes do not have true stems. roots, leaves and vascular bundles. Mosses have a thalloid (stem like structure) and rhizoids (root like structures) which anchor them. Spores are produced in spore sacs. Have no vascular bundles. Gametophytic generation alternates with the sporophytic generation In leafy liverworts the stems-and leaves make up the gametophyte, while the sporophyte is typically a blackish spore capsule. In hornworts the elongated horn-like structure, is the sporophyte. The flattened, green plant body of a hornwort is the gametophyte plant. Pteridophytes are simple vascular plants lacking true roots and, in some species, leaves. They reproduce by spores. They have rhizoids to anchor them. In all Pteridophytes the dominant plant is the sporophyte which produces by spores with the gametophyte which produces male and female gametes Ferns do not have true leaves as many plants do, but have structures called fronds. Ferns reproduce by spores. The fern itself is the sporophyte, which produces asexual spores. The spores are held in special sacs scattered on the bottom part of fronds. Whisk fern is a rootless, green-stemmed epiphyte. The plant is regularly branched, with scale like outgrowths that resemble small leaves. A subterranean rhizome anchors the plant Horse tails resemble the tail of a horse. In these plants the leaves are greatly reduced and are arranged in whorls... Gymnosperms are a group of vascular plants whose seeds are not enclosed by a ripened ovary (fruit). They have true roots, stems and leaves. Conifers have needle-like leaves, spirally arranged. Large trees with woody stems. Do not produce flowers. Stems are usually unbranched. Cycads have palm like compound leaves. Produce seeds in cones The gingko is a tall tree with deciduous fan-shaped leaves; the only living descendant of a once-large group. Produces seeds in cones Gnetophytes are cone-bearing desert plants. Resemble flowering plants in many ways; were once thought to be link between conifers and angiosperms. 3 Class- Angiospermae Flowering plants Subclass- Dicotyledonae (2 cotyledons) Subclass- Monocotyledonae (1 cotyledon) Angiosperms are flowering plants. They have true roots, stems, leaves and flowers. They also have seeds which are enclosed in the ovary. They are divided into monocots and dicots. Dicot flower parts are in multiples of 4 or 5. Leaf veins are net like, seeds have two cotyledons, have tap root system Monocot flower parts are in multiples of 3. Leaf veins are parallel, seeds have one cotyledon, have fibrous roots Method: Note: Plants are classified by observing their physical characteristics and mode of reproduction. 1. Collect various plant specimens and place them on your table. Observe the following features while classifying plants: a. Stem: woody, soft (herbaceous), hollow or solid. b. Roots: fibrous or tap root system c. Leaves: long, narrow or broad, needle like, small or large d. Thallus: leaf like structure e. Rhizoids: root like structures f. Veins: parallel or net like g. Flower parts: multiples of three or multiples of 4 or 5 h. Spores: under the leaf or in spore sacs i. Seeds: inside cones or enclosed in a fruit j. Cotyledons: two cotyledons or one cotyledon k. Vascular tissue: present or absent 2. Look at the external features of each specimen and record your observations in table 1. 3. After completing the table, identify the division and class to which each specimen belongs to. Caution: Do not dispose of plant specimens in the sink. Place them in a specified container. Wash your hands after handling specimens 4 Results: Table 2 –Complete the table with the characteristics of plants: Structures observed Type of stem Thallus Type of Roots Rhizoids Type leaves Moss Liverwort Lichen Fern No true stem No true stem No true stem No true stem Present No true roots Present No true roots Present No true roots Present Present Present Small Liver shaped Crusty leaf like leaves structures Type of Veins Absent Vascular bundles Absent Number of floral parts Absent Pine Has woody stem Geranium Lily Bean Corn Has herbaceous stem Has herbaceous stem Has herbaceous stem Has hollow stem Absent Absent No true roots Has tap root system Absent Has tap root system Absent Has tap root system Absent Has tap root system Absent Has fibrous roots Present Absent Large fronds Needle like leaves Absent Large leaves Absent Narrow long leaves Absent Large leaves Absent Narrow long leaves Absent Absent Absent Absent Net like Parallel Net like Parallel Absent Absent Present Present Absent Absent Absent Absent Present Multiples of 5 Present Multiples of 3 Present Multiples of 5 Present Multiples of 3 Absent Absent Absent Absent Present Absent Absent Absent Absent Spores Present Naked seeds or Absent seeds in a fruit Number of cotyledons Absent Present Present Present Absent Absent Absent Absent Absent Absent Naked seeds in a cone No seeds No seeds Absent Seeds in a pod Absent Seeds on a cob Absent Absent Absent Absent None None Two One Bryophyta Kingdom Pteridophyta Spermatophyta fungi Pteridopsida Gymnosperm Cones Division Class Bryophyta Bryopsida Hepatopsida Spermatophyta Spermatophyta Spermatophyta Spermatophyta Angiosperm Dicot Note Refer to your biology book or ask your teacher to help you when classifying lichen. Angiosperm Monocot Angiosperm Dicot Angiosperm Monocot 5 2. Table 3 Complete the table given below with distinguishing features of three major divisions of plants( Refer to table 1) Spermatophyta Bryophyta Pteridophyta Gymnospremae Angiospermae (mosses, liverworts) (ferns) Cone bearing plants Flowering plants Bryophytes do not have true Pteridophytes have Gymnosperms have Dicotyledonae Monocotyledonae stems, roots and leaves. vascular bundles. Ferns vascular bundles. They Dicots have vascular Monocots have vascular They also do not have have large fronds, but do have large woody stems, bundles. They have woody bundles. They have vascular bundles. They not have true stems and taproots and confers have or herbaceous stems, tap hollow, herbaceous stems, reproduce by spores held in roots. Spores are found in needle like leaves. They roots and large leaves. The fibrous roots and long, spore sacs spore sacs under the have seeds in cones. leaves have net like veins. thin leaves. The leaves leaves. Their flowers have floral have parallel veins. Their parts in multiples of 4 or 5. flowers have floral parts in Their seeds have two multiples of 3. Their seeds cotyledons. have one cotyledon. 3. Convert the branching dichotomous key given in figure 1, to word dichotomous key. 1a. vascular tissue go to 2 1b. no vascular tissue go to Bryophyte 2a. has seeds 2b. no seeds go to go to 3 Pteridophyta 3a. has flowers 3b. no flowers go to Angiosperm 4 go to Fern 5 go to Gymnosperm 6 4a. has large fronds 4b. no large fronds 5a. has cones 5b. has no cones 6a. has seeds in fruit 6b. seeds not in fruit 7a. Has 2 cotyledons 7b. has 1 cotyledon go to 7 Gymnosperm Dicot Monocot 6 Discussion questions: 1. What are the differences between vascular and non-vascular plants? Vascular plants have vascular bundles such as xylem and phloem vessels and non vascular plants do not have vascular bundles. 2. Name two major divisions in phylum Tracheophyta. Pteridophyta (seedless plants) and spermatophyta (plants with seeds) 3. Which characteristics of plants helped you to identify and classify plants? The presence or absence of vascular bundles, external characteristics and their mode of reproduction helped in identifying plants. 4. What are bryophytes? Give three examples. Bryophytes are plants without vascular bundles. They do not have true stem, true roots and leaves. Mosses, liverworts and hornworts are bryophytes. 5 In which major plant group are the following plants classified: (a) Flowering plants- are spermatophytes and angiosperms (b) Conifers – are spermatophytes and gymnosperms c) ferns- are pteridophytes 6. Why are fungi placed in a different kingdom? Fungi are placed in kingdom fungi because they do not have chlorophyll and cannot photosynthesise. They are saprophytes. 7. Why is it difficult to classify lichen? Lichen contains both alga and fungus living together in a symbiotic relationship. So it is difficult to classify them as belonging to kingdom protista or kingdom fungi. But they are placed in kingdom fungi. Conclusion: 1. Which distinguishing features did you use in classifying plants? The following distinguishing features were used in classifying plants: presence or absence of vascular bundles, type of stem, type of roots, type of leaves and the arrangement of veins, presence or absence of thallus, rhizoids, spores, seeds, flowers, cones and number of floral parts and cotyledons. 2. List the differences between bryophyta, pteridophyta and spermatophyta. Spermatophyta Bryophyta Pteridophyta Gymnospremae Angiospermae Cone bearing plants Flowering plants Bryophytes do not have true Pteridophytes have Gymnosperms have Dicots have vascular Monocots have vascular stems, roots and leaves. vascular bundles. Ferns vascular bundles. They bundles. They have woody bundles. They have They also do not have have large fronds, but do have large woody stems, or herbaceous stems, tap hollow, herbaceous stems, vascular bundles. They not have true stems and taproots and confers have roots and large leaves. The fibrous roots and long, reproduce by spores held in roots. Spores are found in needle like leaves. They leaves have net like veins. thin leaves. The leaves spore sacs spore sacs under the have seeds in cones. Their flowers have floral have parallel veins. Their leaves. parts in multiples of 4 or 5. flowers have floral parts in Their seeds have two multiples of 3. Their seeds cotyledons. have one cotyledon. 7 Websites: http://farm4.static.flickr.com/3145/2571238669_a5c5ebb0c3.jpg?v=0 for gnetophyte http://www.gocek.com/christiansymbols/images/wheat.gif for wheat plant http://en.wikipedia.org/wiki/File:Equisetopsida.jpg for horse tail http://www.diytrade.com/china/4/products/122380/Ginkgo_Biloba_Extract.html for ginkgo http://www.liveaquaria.com/images/categories/product/p-11285-hornwort-15498.jpg for hornwort http://www.alientravelguide.com/science/biology/life/plants/tracheo/psilopsi/whiskfer.htm for whisk fern http://www.amnh.org/learn/biodiversity_counts/class_prep/plants.htm ******************* 8