28Gymnosperm

📚
GYMNOSPERMS
▢ Introduction:

Table 1: General Features

Feature
Point
Nature
Naked-seeded plants
Reason
Ovary absent
Plant status
Successful land plants
Main plant body
Sporophyte
Seed
Not enclosed inside fruit
▢ Living Fossils:
❖ Definition: Organisms present in both living + fossil forms with little/no evolutionary change
❖ Examples:
  • •
    Cycas
  • •
    Ginkgo
  • •
    Metasequoia
❖ Correction: Ginkgo is gymnosperm, not angiosperm
▢ Conduction Tissue:

Table 1: Vascular Tissue

Tissue
General condition
Exception / Note
Xylem
Vessels absent
Vessels present in Gnetales
Phloem
Companion cells absent
Albuminous cells/tissue present
Sieve tube
Absent
Sieve cells present
❖ Gnetales with Vessels:
  • •
    Gnetum
  • •
    Ephedra
  • •
    Welwitschia
▢ Habit & Leaf:

Table 1: Habit and Leaf

Feature
Point
Size
Generally large-sized
Branching
Generally branched
Exception
Cycas
Smallest gymnosperm
Zamia pygmaea
Leaf
Unipinnately compound in Cycas
▢ Reproductive Features:

Table 1: Reproduction in Gymnosperms

Feature
Point
Male reproductive structure
Male cone
Female reproductive structure
Female cone
Exception
Female cone absent in Cycas
Pollination
Anemophilous / by wind
Gymnosperm pollination
Transfer of microspore from microsporophyll directly to ovule
Ovule
Mostly orthotropous
Exception
Pinus ovule → anatropous
Mnemonic
PAN → Pinus = Anatropous
Fertilization
Generally siphonogamous
Exception
Cycas → zooidogamous
After fertilization
Ovule → seed
Endosperm
Haploid
▢ Zooidogamy vs Siphonogamy:

Table 1: Types of Fertilization

Type
Meaning
Examples
Zooidogamous
Motile male gamete moves toward female gamete with flagella/cilia
Cryptogams, Cycas
Siphonogamous
Non-motile male gamete carried through pollen tube
Phanerogams except Cycas
▢ Classification:

Table 1: Main Groups of Gymnosperms

Group
Common name
Examples / Points
Cycadopsida
Cycads
Cycas, Zamia pygmaea → smallest gymnosperm
Ginkgopsida
Ginkgo group
Ginkgo biloba → Maiden hair tree
Gnetopsida
Gnetales
Gnetum, Ephedra, Welwitschia → vessels present
Coniferopsida
Conifers
Pinus, Cedrus, Sequoia, Araucaria excelsa, Araucaria imbricata
▢ Important Examples:

Table 1: Examples & Common Names

Plant
Common / Important Point
Ginkgo biloba
Maiden hair tree; living fossil
Zamia pygmaea
Smallest gymnosperm
Araucaria excelsa
Christmas tree
Araucaria imbricata
Monkey puzzle plant
Pinus
Conifer; anatropous ovule exception
Cycas
Living fossil; zooidogamous fertilization; female cone absent
Sequoia
Very tall gymnosperm tree
▢ Tallest Tree:

Table 1: Tallest Tree Points

Plant
Point
Eucalyptus regnans
Tallest angiosperm / flowering tree
Sequoia
Very tall gymnosperm
Sequoiadendron giganteum
Giant sequoia; massive tree
Mangifera indica
Mango; angiosperm
Pinus roxburghii
Chir pine / Rani salla
📚
CYCAS
▢ Classification:

Table 1: Cycas

Feature
Point
Group
Cycadopsida
Example
Cycas revoluta
Living fossil
Yes
Habit
Unbranched tree-like plant
Habitat condition
Physical xerophytic condition
Physical xerophytic
Hot / tropical climate
▢ Plant Body:
❖ Division:
  • •
    Root
  • •
    Stem
  • •
    Leaf
❖ Root:

Table 1: Root of Cycas

Root type
Feature
Coralloid root
Negatively geotropic / apogeotropic
Symbionts
Nostoc + Anabaena
Function
Nitrogen fixation
❖ Stem:

Table 1: Stem of Cycas

Feature
Point
Type
Caudex
Nature
Solid, cylindrical, unbranched
Leaf scars
Present due to persistent leaf bases
Wood
Porous + soft
Commercial value
Less important
❖ Leaf:

Table 1: Leaf of Cycas

Feature
Point
Type
Unipinnately compound
Xerophytic feature
Thick cuticle
Stomata
Sunken stomata
▢ Reproduction:

Table 1: Male vs Female Plant

Feature
Male Cycas plant
Female Cycas plant
Sex
Dioecious male plant
Dioecious female plant
Reproductive structure
Male cone present
Female cone absent
Female structure
—
Megasporophylls loosely arranged
Fertilization
Produces motile male gametes
Zooidogamous fertilization
▢ High-Yield Points:
  • •
    Cycas = living fossil
  • •
    Cycas = zooidogamous fertilization
  • •
    Female cone absent
  • •
    Coralloid root contains Nostoc + Anabaena
  • •
    Stem = caudex
  • •
    Leaf = unipinnately compound
  • •
    Wood = porous + soft
📚
PINUS
▢ Species Found in Nepal:

Table 1: Pinus Species of Nepal

Needles
Species
Common name
3-needled
Pinus roxburghii
Chir pine / Rani salla
5-needled
Pinus wallichiana
Blue pine / Gobre salla
▢ Plant Body:
❖ Nature: Sporophyte
❖ Division:
  • •
    Root
  • •
    Stem
  • •
    Leaves
▢ Root:

Table 1: Root of Pinus

Feature
Point
Root system
Tap root + lateral roots developed
Vascular bundle
Diarch to tetrarch
Vascular bundle type
Radial
Protoxylem
Exarch
Resin canal
Between patches of protoxylem
Pith
Absent or reduced
Stele
Protostele
▢ Stem:

Table 1: Stem of Pinus

Feature
Point
Growth pattern
Monopodial
Main stem
Monopodial + excurrent
Stem nature
Dimorphic
Surface
Wavy due to leaf bases
Secondary growth
Normal
Stele
Eustele
❖ Branches:

Table 1: Branches of Pinus

Branch type
Other name
Feature
Long branch
Branch of unlimited growth
Main vegetative growth
Short branch
Dwarf branch / branch of limited growth
Bears needle-like foliage leaves; falls at maturity
❖ Leaves on Shoots:

Table 1: Leaves of Pinus Shoots

Leaf type
Location
Features
Needle-like foliage leaves
Only on dwarf shoots
1–5 needles per dwarf shoot; thick waxy cuticle; sunken stomata
Cataphylls / scale leaves
Both long + dwarf shoots
Small, brown
❖ Layers Outside to Inside:
  1. Cuticle
  2. Epidermis
  3. Cortex zone
  4. Endodermis
  5. Pericycle → multilayered
  6. Pith → parenchymatous
❖ Vascular Bundle:

Table 1: Stem Vascular Bundle

Feature
Condition
Type
Conjoint
Arrangement
Collateral
Cambium
Open
Protoxylem
Endarch
❖ Wood:

Table 1: Wood of Pinus

Feature
Point
Type
Monoxylic + pycnoxylic
Nature
Compact + hard
Tracheids
Bordered pits present
▢ Sexual Reproduction:
❖ Plant Nature:

Table 1: Reproductive Nature

Term
Meaning
Monoecious
Male + female cones on same plant
Autoecious
Both sex organs on same host plant
Cone position
Male + female cones on separate branches of same tree
❖ Male Cone vs Female Cone:

Table 1: Male Cone vs Female Cone

Feature
Male cone
Female cone
Position
Axils of scale leaves; in clusters
Axils of scale leaves at tip of new strong shoots
Distance
Near male cone region
At some distance from male cones
Development time
Shorter
About 3 years
Nature
Cone with microsporophylls
Modified inflorescence due to presence of bract
Sporangia
Microsporangia
Megasporangia / ovules
Sporangia position
Lower / abaxial side of microsporophyll
Upper / adaxial side of ovuliferous scale
Sporangium development
Eusporangiate
Megasporangiate
❖ Female Cone / Megasporophyll:

Table 1: Female Cone Structure

Part
Point
Ovuliferous scale
Bears 2 naked ovules toward basal region on upper / adaxial side
Bract scale
Supports ovuliferous scale
Ovules / megasporangia
Unitegmic + anatropous
Megaspore formation
By meiosis in megaspore mother cell / MMC
Functional megaspore
Germinates to form female gametophyte
Archegonia
2–5 in number
◉ Archegonium:

Table 1: Archegonium of Pinus

Cell
Number
Neck cells
4 + 4 = 8
Venter canal cell / VCC
1
Egg cell
1
Neck canal cell / NCC
0
❖ Male Gametophyte / Pollen:

Table 1: Pollen Grain of Pinus

Feature
Point
Pollen tube
Acts as sperm carrier
Pollen grain
Winged
Wing origin
Exine
Pollination stage
4-celled stage
4 cells
2 prothallial cells + 1 generative cell + 1 tube cell
Male gametes
2 passive non-motile male gametes formed by body cell division
After pollen tube burst
2 gametes liberated; 1 fuses with egg nucleus; other degenerates
Pollination phenomenon
Atmosphere becomes yellowish → shower of sulphur
◉ Winged Structures:

Table 1: Winged Structures

Structure
Example
Winged pollen grain
Pinus
Winged seed
Moringa
Winged fruit
Hiptage, Shorea
❖ Fertilization & Seed:

Table 1: Fertilization and Seed

Feature
Point
Fertilization time
11–15 months after pollination
Fertilization type
Siphonogamy
Male gamete
Non-motile
Seed maturity
After 3 years of development
Seed germination
Epigeal
Exception
Hypogeal in Cycas
Cotyledons
2–18
▢ High-Yield Points:
  • •
    Pinus roxburghii → 3 needles → Chir pine / Rani salla
  • •
    Pinus wallichiana → 5 needles → Blue pine / Gobre salla
  • •
    Pinus root → diarch to tetrarch + radial + exarch
  • •
    Stem → monopodial + excurrent
  • •
    Stem dimorphic → long shoots + dwarf shoots
  • •
    Needles only on dwarf shoots
  • •
    Wood → monoxylic + pycnoxylic
  • •
    Tracheids with bordered pits
  • •
    Pinus = monoecious + autoecious
  • •
    Female cone = modified inflorescence
  • •
    Each ovuliferous scale bears 2 naked ovules
  • •
    Ovules = unitegmic + anatropous
  • •
    Pollination at 4-celled stage
  • •
    Shower of sulphur → yellow pollen release
  • •
    Fertilization after 11–15 months
  • •
    Seeds mature after 3 years
  • •
    Seed germination = epigeal
  • •
    Cotyledons = 2–18
Q1.
Turpentine oil is obtained commercially from resin of:
📅CEE MBBS 2024B
Q2.
Which structure is absent in gymnosperms?
📅CEE BDS 2024
Q3.
The air sacs or wings of Pinus pollen arise from the:
📅CEE MBBS 2022
Q4.
Gymnosperms are characterized by:
📅CEE MBBS 2022
Q5.
Gymnosperm seeds are naked because gymnosperms lack a(n):
📅CEE MBBS 2021
Q6.
How many ovules are usually borne on each ovuliferous scale of a Pinus female cone?
📅MOE 2008
Q7.
The male gametes of Cycas are:
📅MOE 2008
Q8.
Which gymnosperm is commonly called a living fossil?
📅MOE 2061
Q9.
Gymnosperms were especially predominant during the:
📅MOE 2002
Q10.
How many needles occur in each dwarf shoot (fascicle) of Pinus roxburghii?
📅MOE 2058
Q11.
The nutritive tissue traditionally called endosperm in a Cycas seed is:
📅MOE 2057
Q12.
Exceptionally large motile spermatozoids occur in:
📅MOE 2057
Q13.
In Cycas, megasporophylls are arranged in a:
📅MOE 2055, 2056
Q14.
A compact male cone is found in:
📅MOE 2054
Q15.
Which feature is NOT characteristic of Cycas?
📅MOE 2053
Q16.
The principal water-conducting elements of typical conifer wood are:
📅IOM 2004
Q17.
Chilgoza, the edible pine nut, is obtained from:
📅IOM 2003
Q18.
Which of the following is absent from the phloem of gymnosperms?
📅IOM 2001
Q19.
An ovary is absent in:
📅IOM 2001
Q20.
The green foliage leaves of Cycas are:
📅IOM 1998
Q21.
Which plant produces seeds but not fruits?
📅BPKIHS 2000
Q22.
The gymnosperm structure most directly comparable to a stamen is the:
📅BPKIHS 2005
Q23.
Wood of most conifers is commercially classified as:
📅IE 2001
Q24.
Transfusion tissue is characteristically found in the leaflets of:
📅IE 2002
Q25.
In conifers, reproductive sporangia are borne on:
📅IE 2002
Q26.
The female gametophytic tissue retained in a gymnosperm seed is traditionally called:
Q27.
Among these plants, which has exceptionally large ovules?
📅IE 2004
Q28.
Pollen exine resists desiccation and environmental damage because it contains:
📅IE 2004
Q29.
The wood of Cycas is described as:
📅IE 2004
Q30.
In gymnosperms, the tissue traditionally called endosperm:
📅IE 2008
Q31.
Why is Cycas not classified as a dicotyledonous angiosperm despite having two cotyledons?
📅BPKIHS 2015
Q32.
Gymnosperms differ from angiosperms primarily in the:
📅BPKIHS 2011
Q33.
Turpentine oil is commercially obtained from resin of:
📅BPKIHS 2010
Q34.
Gymnosperms are called naked-seeded plants because they lack:
📅IOM 2013
Q35.
Angiosperms differ from gymnosperms in having:
📅IOM 2016
Q36.
How many needles occur in one fascicle of Pinus roxburghii?
📅MOE 2014
Q37.
Which listed gymnosperm is generally cultivated rather than native to Nepal?
📅MOE 2014
Q38.
Winged (saccate) pollen grains are characteristic of:
📅MOE 2068
Q39.
The ovule of Cycas is typically:
📅MOE 2010
Q40.
Turpentine oil is obtained from:
📅MOE 2010