Ch 2Plant Kingdom — Class 11 Botany, concept-first.

Organisms on Earth were traditionally sorted into just two groups, plants and animals, based mainly on how they get their nutrition, whether they can move about, and whether their cells carry a wall -…

Older classification schemes lumped plants and animals apart mainly by nutrition (photosynthetic vs. ingestive), locomotion (fixed vs.

Alternation of generation is the defining rhythm of every plant life cycle: a haploid (n), gamete-producing gametophyte phase alternates with a diploid (2n), spore-producing sporophyte phase.

Algae are the simplest chlorophyll-bearing, photosynthetic organisms in the plant kingdom — they lack true roots, stems and leaves, yet together they are responsible for more than half of the world's…

Algae show one of the widest ranges of body form (thallus organisation) in the plant kingdom, running from single free-swimming cells to giant kelps many metres long.

F.E. Fritsch classified the algae into eleven classes based on their photosynthetic pigments, the number and type of flagella, the chemical nature of the stored food reserve, thallus organisation and…

Algae have real commercial and ecological value beyond their role as primary producers. Several genera (Chlorella, Laminaria, Sargassum, Ulva, Enteromorpha) are eaten directly as food.

Oedogonium (Class Chlorophyceae, Order Oedogoniales) is a freshwater, filamentous green alga found attached to rocks in ponds, lakes and still water; some species are epiphytic on other aquatic plants…

Chara (Class Chlorophyceae, Order Charales), popularly called 'stonewort', is a submerged freshwater alga anchored in the mud of lakes and slow streams (C.

Bryophytes are often nicknamed the 'amphibians of the plant kingdom' — like amphibians, they can live on land but still depend on the presence of water (specifically, a thin film of water) to complete…

Bryophytes are simplest land-dwelling cryptogams, mostly confined to moist, shady habitats, though a few (Riella, Ricciocarpus) are aquatic.

Proskauer (1957) organised Bryophyta into three classes, distinguished chiefly by how differentiated the gametophyte is and by the structure of the sporophyte. Hepaticopsida (liverworts), e.g.

Bryophytes, especially Sphagnum, have real economic weight despite their small size. Large amounts of dead Sphagnum thallus accumulate, compress and harden into peat, which is burned as fuel on a comm…

Marchantia (Class Hepaticopsida, Order Marchantiales) grows in cool, moist, shady places; Marchantia polymorpha is the commonest species.

Funaria (Class Bryopsida, Order Funariales), commonly called 'cord moss', is a worldwide moss; Funaria hygrometrica, the common species, grows in tufts on rocks, tree trunks and damp walls/soil, and c…

Pteridophytes are considered the first true land plants and — crucially — the first plant group to evolve real vascular tissue (xylem and phloem), which is why they are also called 'vascular cryptogam…

In pteridophytes the sporophyte (2n) is the dominant, long-lived, independent phase, and it is differentiated into true root, stem and leaves — a real step up from the bryophyte body plan.

Reimer (1954) classified the pteridophytes into five subdivisions spanning 19 orders and 48 families. Psilophytopsida is entirely extinct — its members (e.g.

Pteridophytes have several practical uses: Rumohra adiantiformis (leather-leaf fern) is grown for cut-flower arrangements; Marsilea is eaten as food; Azolla is used as a biofertiliser (thanks to its s…

Selaginella (Division Lycophyta, Order Selaginellales), commonly called 'spike moss', grows in humid temperate and tropical rainforests; S. rupestris and S.

Adiantum (Division Pteropsida, Order Filicales), the 'maidenhair fern' (also called 'walking fern'), grows across the tropics and temperate zones; Indian species include A. capillus-veneris, A.

The term stele refers to the central cylinder of vascular tissue running through a root or stem — xylem, phloem, pericycle and, in some forms, medullary rays and pith.

Gymnosperms (Greek gymnos = naked, sperma = seed) are 'naked-seed' plants — their ovules, and later their seeds, sit exposed rather than being enclosed inside an ovary.

Most gymnosperms are evergreen, woody trees or shrubs (a few, like Gnetum, are lianas), with a sporophyte differentiated into root, stem and leaves.

Sporne (1965) classified the gymnosperms into three classes spanning nine orders and thirty-one families. Cycadopsida (e.g.

Gymnosperms and angiosperms are grouped together as the seed plants (spermatophytes) because they share several important features: both have a well-organised plant body differentiated into root, stem…

Gymnosperms supply a wide range of everyday products relative to their small species count. Cycas circinalis and C.

Cycas (Class Cycadopsida, Order Cycadales) is widely distributed across the tropical and sub-tropical eastern hemisphere; C. revoluta, C. beddomei, C. circinalis and C. rumphii are common species.

Pinus (Class Coniferopsida, Order Coniferales) is a tall, conical, evergreen tree forming dense forest across the North temperate and sub-alpine world, usually at 1,200–3,000 m altitude; species inclu…

Angiosperms are seed plants whose ovules are fully enclosed inside a protective ovary, unlike the naked ovules of gymnosperms — this is what the name literally reflects.

Angiosperms show several defining features that set them apart from every other plant group covered in this chapter. Their vascular tissue (xylem and phloem) is well developed.

Dicotyledons and Monocotyledons differ consistently across both their external (morphological) and internal (anatomical) features.

This end-of-chapter Evaluation exercise checks understanding across the full sweep of the chapter — from the classification and life-cycle patterns that apply to every plant group, through algal thall…

Sample papers and previous-year board questions for this subject.