The Plant Kingdom - cryptogams and phanerogams

The Plant Kingdom – cryptogams and phanerogams

Plant Kingdom

In the plant kingdom, plants are classified into various divisions and subdivisions based on their similarities and dissimilarities. The branch of science, dealing with classification of plants is called Plants taxonomy. The study of plants is called Phytology.

Eichler (1883) divided plant kingdom into two subkingdoms (Cryptogams and Phanerogams). Cryptogamae (having conspicuous reproductive structures) with plants having no flower such as algae, fungi, bryophyte and pteridophytes and Phanerogamae (having visible reproductive structures) with plants having evident reproductive organs like flowers and seed such as angiosperms and gymnosperms (BECE 2012).

Algin is extracted from brown algae, e.g. Laminaria seaweed, etc. It is a hydrocolloid used in shaving creams, jellies, flameproof plastic, etc. The carrageenan is extracted from red algae like Chondrus and used as emulsifier and clearing agent (NEET – II 2016).

Conifers are gymnosperms. Their leaves show xerophytic adaptations. The leaves are needle-like with thick walled single layered epidermal cells covered with the thick cuticle. This enables them to tolerate extreme climatic conditions (NEET – II 2016).

Sequoia is one of the tallest tree in plant kingdom, commonly known as the redwood tree. It is a gymnosperm plant like Ginkgo and Pinus and the Salvinia is a pteridophyte. Gymnosperms are well adapted to extremes of climate and are heterosporous (NEET – I 2016).

Gymnosperms are vesselless plants, like pine (AMU 2015).

In Funaria 8-10 neck canal cells are found (Chattisgarh PMT 2015).

Selaginella species are creeping or ascendant plants that produce heterosporous (megaspores and microspores). The coralloid roots are developed in Cycas. They are produced as the cluster at the base of the stemThey are dichotomously branched and greenish brown in color. They contain algal zone in the cortex. This algal zone contains Nostoc and Anabaena, which grow in symbiotic association with coralloid root (CBSE AIPMT 2015).

Peat is mainly an accumulation of partially decayed vegetation or organic matter and Sphagnum. This accumulation can store water since both its living and dead constituents can hold large quantities of water and living matter (like meat and eggs) for long distance transport inside their cells. Hence, it is responsible for peat formation (CBSE AIPMT 2015).

Lilium (angiosperm) possesses the male gametophyte with least number of cells. The number of cells is male gametophyte shows the pattern of reduction from bryophytes to angiosperms. In angiosperms, it is reduced to about 2-3 celled, and called as pollen grains. The number of cells in male gametophyte decreases in the following order Funaria > Pteris > Pinus > Lilium (CBSE AIPMT 2015).

Bryophytes are archegoniate (Female gametophyte), tracheophytes (absence of vascular elements) and embryophytes. Bryophytes are small non-vascular plants. They are herbaceous plants that grow closely packed together in mats or cushions on rocks and soil, e.g. Ferns, mosses, etc. They have the life cycle with alternation of generation. The life cycle goes through both gametophytic (haploid) and sporophytic (diploid) stage (EAMCET 2015).

Pteridophytes are the most primitive vascular plants on earth and are known as vascular cryptogams. They were the first vascular plants to grow and began their life period from leafless or rootless individuals. They played an important part in the establishment of the early land flora as they emerged shortly after the evolution of land plants and are much larger than Bryophyta(which are non-vascular plants) (EAMCET 2015).

Bryophytes are characterized by the presence of an independent gametophyte and parasitic sporophyte. They live in soil but are dependent on water for sexual reproduction. Thus, are called amphibians of the plant kingdom (Kerala CEE 2015).

Both antheridium and oogonium are the male and female reproductive structures respectively in Chara. They have sterile jackets on their surface. In globule, the male sex organ is found on the lower side, while the female sex organ is present on the upper side of vegetative (leaf-like) structures (CBSE AIPMT 2014, NEET 2013).

Volvox forms the motile colony. A typical Volvox colony is holosphere of mucilage have 500 or more biflagellate algal cells. This combined beating of their flagella causes the colony to glide slowly through the water. Large colonies can reach a diameter of a millimeter or so (Manipal 2013).

The alginic acid of alginate is found in the cell walls of seaweeds, such as Laminaria, Macrocystis, Ascophyllum, etc (UP CPMT 2013, 2009).

The dominant phase in the life cycle of pteridophyte is sporophyte(2n), which is generally herbaceous, rarely woody. The plant body is differentiated into roots, stems, and leaves. The main plant body of bryophytes is gametophytic, which is independent. True roots are always absent, but unicellular or multicellular rhizoids are found (UP CPMT 2012).

There are two generations in the life cycle of bryophytes. The main plant body is gametophytic, The gametophytic phase starts with the formation of spores, Which generate bryophyte thallus. The antheridium (male sex organ) produces the egg, which undergoes fertilization to form the zygote, The sporophytic phase starts with zygote and ends with reduction division in spore mother cells (UP CPMT 2012).are naked seeded plants, in w

In gymnosperms, ovule is not covered by the ovary, they are naked seeded plants. The xylem of gymnosperms contains only xylem parenchyma and tracheids. The vessels are absent in gymnosperms (except Gnetales) (UP CPMT 2012).

Bryophyta is a group of embryo producing plants, which do not bear fruits seeds and any vascular tissue, They are known as ‘amphibians of plant kingdom’. Body is thalloid and gree (due to the presence of chloroplast). The male sexual organ is antheridium and female sexual organ is archegonium (BCECE 2012).

The pteridophytes exhibit alternation of the dominant sporophytic generation with an inconspicuous gametophytic generation. The sporophyte is differentiated into root, stem and leave, while the small and inconspicuous gametophyte is independent and autotrophic (BCECE 2012).

Sphagnum is known as peat moss. The partially decomposed Sphagnum accumulates to form compressed mass called peat (Manipal 2012).

Spores of Funaria,  on germination, gives rise to protonema (Manipal 2012, OJEE 2011).

Pteridophyta is a group of non-deed forming, vascular cryptogams, i.e. these contain vascular tissues for the conduction of minerals and water, but do not produce seed (Manipal 2012).

Gametophyte and sporophytic phase are present in the life cycle of bryophytes and both phases are morphologically distinct. The gametophytic phase is more conspicuous independent and dominant, while sporophyte depends on the gametophyte (UP CPMT 2011).

Some of the pteridophytes produce smaller spores called microspores and the larger one called megaspore. This nature is called heterospory. In angiosperms, there is only one functional megaspore. The male and female gametes fuse to form a zygote, which eventually develops into an embryo. The embryo forms the seed (OJEE 2011).

Brown algae (Laminaria) are rich in sodium, potash, and iodine. About 7% of total world production of iodine is obtained from kelps (brown algae) in Japan (OJEE 2011).

Fern gametophyte is homothallic, It bears male and female sex organs in the same plant (OJEE 2010).

In bryophytes, the zygote is the beginning of the sporophytic generation. within the center of the archegonium, the zygote undergoes segmentation and develops without a resting period into a multicellular, undifferentiated structure called embryo. The embryo by further segmentation and differentiation finally develops into a full-fledged sporophyte called sporogonium. The cell of sporogonium undergoes meiosis to produce spores (OJEE 2010).

In Cyca, pollination occurs at the three-celled stage. Microspore shed from the microsporangium at the three-celled stage, i.e. prothallial cell, tube cell and the generative cell (OJEE 2010).

The sporophyte of Funaria consists of a foot, a long slender seta and a capsule. The capsule wall is several layers thick and is highly differentiated, The outermost layer is the apophysis region, fever in the theca region and none in the opercular region (UP CPMT 2009).

In moss (Funaria), the dispersal of spores is facilitated by hygroscopic pouring movement of peristomial teeth (lengthening and shortening of peristomial teeth). The inner peristome act as a sieve allowing only a few spores to escape a time (MP PMT 20019).

In pteridophytes, spore is a haploid structure (MP PMT 2009).

Gelidium, Gracilaria, Pterocladia are red algae having industrial importance. They produce a jelly-like substance agar-agar, used as culture medium (UP CPMT 2009).

Cycas resembles with the angiosperm, due to the presence of siphonogamy, i.e. male gametes are carried to the female gamete through pollen tube. Vessels are present the xylem of angiosperm, while absent in Cycas (Gymnosperm) (UP CPMT 2008).

In the prothallus of a vascular cryptogam, the antherozoids and eggs mature at different times. As a result, self-fertilization is prevented (CBSE AIPMT 2007).

In gymnosperms, the pollen chamber is a cavity in the ovule, in which pollen grains are stored after pollination (CBSE AIPMT 2007).

Biological Classification

The Animal Kingdom

Quick Revision – The Plant Kingdom