Glossary: Plant Kingdom | Biology for Grade 11 PDF Download

Plant Kingdom

• Artificial System: The earliest systems of classification used only gross superficial morphological characters such as habit, color, number and shape of leaves, etc. They were based mainly on vegetative characters or on the androecium structure. Such systems were artificial; they separated the closely related species since they were based on a few characteristics.
• Natural Classification Systems: Based on natural affinities among the organisms and consider, not only the external features, but also internal features, like ultrastructure, anatomy, embryology and phytochemistry. 
• Phylogenetic Classification Systems: Phylogenetic classification systems based on evolutionary relationships between the various organisms are acceptable. This assumes that organisms belonging to the same taxa have a common ancestor.
• Numerical Taxonomy: Numerical Taxonomy which is now easily carried out using computers is based on all observable characteristics. Number and codes are assigned to all the characters and the data are then processed. In this way each character is given equal importance and at the same time hundreds of characters can be considered.
• Cytotaxonomy: Cytotaxonomy is based on cytological information like chromosome number, structure, behaviour.
• Chemotaxonomy: Chemotaxonomy that uses the chemical constituents of the plant to resolve confusions.

Algae

• Zoospores: Asexual reproduction is by the production of different types of spores, the most common being the zoospores.
• Isogamous: Sexual reproduction takes place through fusion of two gametes. These gametes can be flagellated and similar in size (as in Ulothrix) or non-flagellated (non-motile) but similar in size (as in Spirogyra). Such reproduction is called isogamous.
• Anisogamous: Fusion of two gametes dissimilar in size, as in species of Eudorina is termed as anisogamous.
• Oogamous: Fusion between one large, nonmotile (static) female gamete and a smaller, motile male gamete is termed oogamous, e.g., Volvox, Fucus.
• Green Algae: The members of chlorophyceae are commonly called green algae.
• Brown Algae: The members of phaeophyceae are called brown algae.
• Red Algae: The members of rhodophyceae are commonly called red algae because of the predominance of the red pigment, r-phycoerythrin in their body.

Bryophytes

• Amphibians of the plant kingdom: Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction.
• Gametophyte: As main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte.
• Antheridium: The male sex organ is called antheridium.
• Archegonium: The female sex organ called archegonium.
• Sporophyte: . An antherozoid fuses with the egg to produce the zygote. Zygotes do not undergo reduction division immediately. They produce a multicellular body called a sporophyte.
• Gemmae: Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialised structures called gemmae.
• Gemma cups: Gemmae are green, multicellular, asexual buds, which develop in small receptacles called gemma cups located on the thalli.
• Protonema stage: The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages. The first stage is the protonema stage, which develops directly from a spore.
• Leafy stage: The second stage is the leafy stage, which develops from the secondary protonema as a lateral bud.

Pteridophytes

• Sporophyll: The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls.
• Prothallus: The sporangia produce spores by meiosis in spore mother cells. The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus. 
• Homosporous spores: In majority of the pteridophytes all the spores are of similar kinds; such plants are called homosporous.
• Heterosporous spores: Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores, are known as heterosporous.

Gymnosperms

• Male strobili: The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili.
• Female strobili: The cones bearing megasporophylls with ovules or megasporangia are called macrosporangiate or female strobili.
• Ovule: The nucellus is protected by envelopes and the composite structure is called an ovule. The ovules are borne on megasporophylls which may be clustered to form the female cones. 

Angiosperms

Flowers: In the angiosperms, the pollen grains and ovules are developed in specialised structures called flowers.