| Talk about plants in general. | Come from common ancestors (green algae).
Multicellular photoautotrophic eukaryotes. Cells are grouped to form functional tissues are grouped to form organs of plant body. Considered as cromophytes since they possess an erect stalk. Plants are all multicellular; cells contain vacuoles and surrounded by cellulosic wall. Autotrophic and feed by photosynthesis (chlorophyll a and b and carotenoids) and carbohydrate stored is starch in chloroplast and other plastids. Majority is terrestrial by there are some aquatic. |
| Talk about Adaptations to land colonizations. | Land colonization was marked by differentiation of specialized structures for photosynthesis, support and anchor to ground.
Leaves, photosynthetic areas are provided with pores allowing gas exchange.
Stems and leaves are covered by cuticle, preventing water loss.
Lignin thickening of cellulosic walls confers rigidity allowing support of aerial organs and the upright shape.
Differentiation of conducting tissues (Xylem and phloem) is essential for transport of viral elements (water, minerals, products of photosynthesis) through plant organs.
Roots improve ground mounting, absorption of water and mineral nutrition
Simultanously we have devices that adapt to terrestrial conditions that appear, allowing greater protection of reproductive cells, embryos and spores. |
| How is the development cycle of plants? | Two heteromorphic alternating generations
Haploid Gametophyte
Diploid Sporophyte. |
| How can plant kingdom be classified? | According to:
Tissue structure (non vascular plants- bryophytes- and vascular plants)
reproductive characteristic (non-flowering and flowering)
reproducing through spores or seeds
seed structure: naked or covered seeds inside a fruit. |
| Classify Bryophytes | Non-vascular:
Bryophytes ( Bryopsida- Mosses- / Hepaticopsida- Liverworts-/ Anthoceropsida- Hornworts) |
| Classify pteridophytes | Pteridophytes (psilotopsida- whisk ferns/ Lycopodiopsida- Club Mosses-/ Sphenopsida- Horsetails-/ filicopsida- Ferns) |
| Classify spermatophytes. | Spermatophytes (Gymnosperms (coniferopsida-Conifers/ Cycadopsida- Cycas/ Gingkopsida- Ginko/ Gnetopsida- Clamydosperms) |
| Classify angiosperms | Angiosperms (Magnoliopsida Dicotyledon (Dicots)
Liliopsida Monocotyledon (MONOCOTS) |
| Talk in general about bryophytes. | Transitional between green algae and vascular plants. First embryophytes or archegonaites, gradually adapted to terrestrial environment.
Chlorophyll cromophytes, they have an erect stalk or cromus, provided with lateral appendages. epidermis is deprived of stomata (pores with some exceptions). Perforations or pores allow gas exchange between atmosphere and internal tissuesof the plant. No roots, but rhizoids which attach to substrate and partially water uptake. Small plants cryptogams and no real tissues or vessels |
| Talk about the development cycle of Bryophytes. | Haploid Generation: Gamete producer corresponding to gametophyte (vegetative apparatus) Gametes are formed inside gametangium protected by wall consisting of one or more cell layers. Male is called antheridia produce mobile sperm, Female called archegonia produces an egg.
Diploid generation; Sporophytes that correspond to spore producer, sporophyte grows as a parasite on female gametophyte from which it takes nutrients and water. |
| How are Bryophytes found in nature? | Form more or less dense carpet in under storey rich in humus
Form low vegetative cover or moss layer in wet or swampy stations, walls and rocks. Able to withstand long periods of drought by dehydrating and rehydrating of favorable conditions (reviviscence) |
| Talk about the class of Bryopsida. | AKA Mosses, most common ones, gametophyte is composed of an upright stem like structure on top of which are found reproductive organs. Axis (cormus) bares leafy blade. Rudimentary structures with no stomata or veins and always one cell thick except for midrib. Leafy blade cells usually contain numerous chloroplasts except midrib. Ground mounting is ensured by multicellular hairs named rhizoids. |
| What does the bryopsida sporophyte include? | Develope female gametophyte, epidermis shows stomata
- Haustorial foot (anchors sporophyte to female gametophyte which absorbs nutrients and water)
- Seta or stalk (holding the capsule)
- Capsule ( covered externally by a membranous or hairy hood called calyptra. Apex of sporangium differentiates into a cap like lid called operculum. which separates it from rest of sporangium as cells torn apart, Cells breakage is precise, resulting in one or two rows of complex teeth called peristome teeth, which respond to humidity being outward when air is dry and spores are released. |
| Describe spore germination. | Immediate if conditions are available, each spore gives a branched and chlorophyllous multicellular filament Protonema, on backside of which appears rhizoidsl upperside is starting point of gametophytes. |
| Talk about the class of Hepaticopsida. | Liverworts, grow in humid environments, gametophytes develop directly from spores, two groups according to vegetative structure (Thalloid and leafy) |
| Talk about thalloid liverworks. | Best known Marchantia, vegetative apparatus is represented by creeping chlorophyllous thallus branched dichotomously and fixed by rhizoids. |
| Talk about leafy liverwort. | Creeping axis with dorso ventral symmetry leaf like structures and rhizoids vegetative apparatus. |
| Talk about Anthoceropsida. | AKA Hornworts, few species, gametophyte in form of rosette, bears on dorsal side archegonia and antheridia and on ventral side unicellular rhizoid that anchor to substrates. Sporophyte is composed of a foot (no seta) and long cylindrical capsule, epidermis shows stomata, several sporophytes can grow on the same gametophyte , cells have large chloroplast with pyrenoid. |
| Talk about Roots of vascular plants. | Anchor and absorption role, they can sometimes store food as well and serve in asexual reproduction.
Two types: Taproot (one principal and many secondary ones)
Fibrous root (numerous primary ones) |
| Talk about the stems of vascular plants. | Produce and support new leaves, branches and flowers. place them in positions where they can function more efficiently; and to transport material to and from roots. Serve to store and transport food minerals and water (Xylem and phloem) carry on photosynthesis and reproduce new plants. Region where leave is attached is called nod, region between nodes is called internode. terminal or axillary bearing of flowers.. |
| Talk about leaves of vascular plants. | Intercept light, exchange gases and provide site for photosynthesis, some also store food and water, provide support or form new plants.
Leaf has flattened blade and attached to twig by petiole.
Within it there are veins, each angle between petiole and stem is called axil and contains bud.
Arrangement of veins (venation) may be pinnate (one primary and many secondary) or palmate (several primary) or parallel. |
| Talk in general about pteridophytes. | They have stems, leaves and roots, they are vascular cryptogams, without flowers or seeds but have conductive tissues (xylem impregnated with lignin)
Their development cycle is very similar to the one of bryophytes with one difference: perennial plant dominating the cycle to the sporophyte, while gametophyte or prothallus is small and has a limited life. Gametophyte is directly derived from the germination of spores.
They have 3 tissue types, protective, ground and conductive tissues |
| Talk about different classes of pteridophytes. | Most primitive one (whisk ferns) do not have leaves or roots, more complex groups (club mosses, horsetails...) have small leaves without petiole with one vein, called microphylls, for the most evolved ones (ferns) have most developed leaves, called megaphylls or fronds with petiole and limbo with a network of veins and the leaves are inserted on rhizomes.
Fertile leaves holding sporangia are called sporophylls.
They can be isosporic: identical spores that give one kind of prothallus bearing antheridia and archegonia
Heterosporic: with microspores and megaspores that give two kinds of prothalli, one bears the antheridia and the archegonia. |
| Talk about Psilotopsida | AKA whisk ferns, sporophyte is formed of upright green stems, branched dichotomously, attached by a rhizome (underground stem) with rhizoids.
Stems are photosynthetic organs since they have no leaves, they have enations, which are green leaflike veinless, photosynthetic flaps of tissue. Sporangia are trilocular (3 lobes) and are born on the short lateral branches directly on the stems, they are isosporic. |
| Talk about the class of lycopodiopsida. | Sprorophyte is fixed to the ground by underground rhizomes holding roots. Branched stems carry microphylls, sporophylls bare sporangia grouped in conelike strobili
Two main genus (Lycopodium (club mosses) and selaginella (spike mosses)) |
| Talk about lycopodium | The strobili are located at the tips of the stems, isosporic, one type of sporophylls and produce one type of spores. |
| Talk about selaginella | AKA spike mosses, strobili are formed of microsporophylls where microspores are formed, and macrosporophylls where macrospores are formed after meiosis that develope antheridia and archegonia respectively. |
| Talk about the class of sphenopsida | AKA equisetum or Horsetail.
Aerial stems grow from the rhizomes bearing roots, aerial stems have nodes, internodes and ribs. Some species have fertile and sterile stems rising from the rhizome. The chlorophyll vegetative stem (non reproducing) bear small non photosynthetic leaves, microphylls, arranged in whorls on the nodes. In some species, lateral branches are inserted at the nodes. Fertile stems are not photosynthetic and have at their end sporangia grouped in strobili. Horsetail is isosporic, bisexual gametophytes are green and independent of sporophyte) |
| Talk about the class of filicopsida | sporophyte of ferns has an underground rhizome. The rhizome carries on its backside adventitious roots. The large leaves or fronds are megaphylls. Ferns are the only vascular cryptogams to have well-developed megaphylls. Commonly fronds are compound; lamina is divided into leaflets, or pinnae, which are attached to the rachis, and extension of the leaf stalk, or petiole. Fronds emerge by Circinnate vernation, uncoiling process. The tips of young fern fronds are called fiddleheads.
Sporangia are grouped in clusters called sori on the backside of sporophylls. The sorus usually has a protective layer termed indusium. Most of them are isosporic others are heterosporic.
Gametophytes or prothallus, with flattened heart-shaped structures has many rhizoids. |
| Talk about the phylum of spermatophytes. | Seed plants, phanerogams. Seeds replace the spores in the developmental cycle. Male and female gametophytes are very small and develop inside specialized organs in the sporophyte which gives them protection against desiccation... After fertilization, the ovule becomes a seed.
All spermatophytes posses megaphylls, but are transformed into needles or scales in some groups. The spermatophytes are divided into two sub-phylums: angiosperms and gymnosperms |
| Talk about the sub-phylum of gymnosperms. | AKA naked seeds, points to one of the principle characteristics of plants belonging to this sub-phylum, that their ovule and seeds are exposed on the surface of modified leaves known as sporophylls. Ovule is not enclosed in an ovary. The seed is formed from the ovule but there is no fruit. They lack specialized water-conducting vessels of flowering plants but have tracheids.
They include four classes. |
| Talk about Cycadopsida. | The plants are fairly large with a short, stout unbranched trunk. The trunk has a terminal crown of long, leathery leaves giving it the appearance of palm tree. Cycads are dioecious: male and female reproductive organs are found on separate plants. |
| Talk about Ginkgopsida | Fossils, represented by single extant species, Ginkgo biloba.
The veins branch dichotomously, a unique leaf venation pattern. A ginkgo can always be identified from its fan shaped leaves. Ginkgos are dioecious, with separate male and female plants.
Can reach large sizes. lose their leaves in autumn, often used as ornamental plant in urban areas because it resists air pollution and other environmental aggressions. |
| Talk about the class of Gnetopsida | Some common characteristics with gymnosperms and some with angiosperms. They are unique among gymnosperms in having vessels in their xylem. three genus:
Gentum: shrubs or vines with large leathery leaves.
Ephedra: much branched shrubs with scaly leaves.
Welwitshia: Most of its body is a long underground taproot. Its short, wide stem forms a shallow disc from which two ribbon like leaves extend. |
| RTalk about the class of coniferopsida. | Largest and most widespread among gymnosperms, Pine, Fir, Spruce, Larch, Cypress...
They are named conifers because their reproductive organs are grouped inside unisexual cones composed of scales. The leaves are either tough needles or scale like well adapted to drought. The xylem of conifers is composed of tracheids. Resin canals are found in stems and leaves, hence the appelation of resinous. Most of them are evergreen (3 remains green by growing leaves along all year long as other leaves fall off.)
few are deciduous (lose leaves in autumn)
They are generally monoecious (trees hold male and female reproductive system) but some species are dioecious. |
| Talk about the subphylum of Angiosperms. | The main feature is the typical flower containing the reproductive organs. Angiosperms are the most diverse group, and the most advanced of plant kingdom. They include both herbaceous and woody plants. In angiosperms the bi-integumented ovule are enclosed in a protective envelope, the carpel, more or less closed in an ovary.
After fertilization, the ovary becomes a fruit and the ovule a seed. This group is characterized by a particular mode of fertilization: double fertilization. Wood is mainly comprising heterogenous real vessels and fibers. |
| Talk about the composition of flowers. | Four floral whorls inserted on the receptacle. These whorls are from the outside to the inside.
-Sepals: mostly green, which together form the calyx
-petals: usually colored, which together constitute the corolla.
The calyx and corolla are sterile protective parts and do not have a reproductive role. Together they form the perianth.
-Stamens: male reproductive system which together form the androecium (filament and Anther)
-Carpels: female reproductive system, which together form the gynoecium or pistil. Each carpel is formed of a lower part, the ovary containing one or more ovule, an upper part, the stigma which receives the pollen grain. Pollination (transport of pollen to male reproductive system) is done by wind, animals.. |
| Talk about liliopsida | Monocots.
One cotyledon, Herbaceous, fibrous root system, number of floral parts by three. leaves with parallel veins, conductive tissues of stems are numerous and scattered |
| Talk about Magniliopsida. | Two cotyledons, Herbaceous or woody plants, taproot system usually present, number of floral parts four or five, leaves with retculate veins, primary growth conductive tissues of the stems are arranged in a ring.
Secondary tissues and cambium. |
