Types of Geophytes and Plant Propagation Methods in Botany

what are the six types of geophytes

1. bulbs

2. corms

3. tubers

4. tuberous roots

5. swollen hypocotyl

6. rhizome

what is a bulb

a short stem (basal plate) surrounded by fleshy, modified leaves called scales

draw a bulb parts

what is a tuber

swollen, modified stem that functions as an underground storage organ

what are examples of tubers

potatoes, caladiums, artichoke

how are tubers propagated

division and tuber nodal cutting

what is a corm

swollen base of a stem axis enclosed by dry scale-like leaves

what is a tuberous root

NOT STEMS. fleshy thickened root

examples of tuberous roots

sweet potato and dahilas

bulb picture

corm picture

tuber picture

tuberous roots picture

swollen hypocotyl

rhizome picture

what us a swollen hypocotyl

flattened, swollen stem produced by enlargement of the hypocotyl (below the cotyledon)

examples of swollen hypocotyl

beets, begonia

what is a rhizome

specialized stem structure in which the main axis of the plant grows horizontally at or below the soil surface

examples of rhizome

bamboo, iris, canna

what are two ways of basal cutting

scooping and scoring

what is scooping

-a type of basal cutting, removal of the entire basal plate.

-Adventitious bulbs (bulblets) develop on cut scales (modified leaves)

what is scoring

- a type of basal cutting, cutting through the basal plate

-promotes development of axillary buds

why can scoring be bad

It damages the apical meristem and eliminates apical dominance

What are the two types of bulbs

tunicate and nontunicate

what is a tunicate (type of bulb)

-membranous outer bulb scales (tunic)

-fleshy concentric inner scales

what is nontunicate (type of bulb)

- no dry membranous covering

-scales loosely arranged

normal offset picture

stem bulblets

scaling and twin scaling picture

(NEEDS PICTURE HERE)

basal cutting

(needs picture here)

what are the four type of propgation of bulbs

-normal offset

-stem bulblets

-scaling and twin scaling

-casal cuttage

what is layering

another type of vegetative prop, it is the rooting of a propagule while it is still attached to the mother plant

layering picture example

sporogenesis def

development of pollen mother cell into pollen grains and megaspore mother cells into the 8-nucleate embryo sac

pollination def

Transfer of pollen from anther to the stigma

fertiliation def

fusion of gametes to form a zygote

what is double fertiziliation

- 1 sperm (1x) fuses with an egg (1x) to form zygote (2x embryo)

- then another sperm (1x) fuses with the 2 polar nuclei (each 1x) which develops endosperm (3x)

draw a diagram of the alternation of generations

draw the mature gametophytic stage of a fern

what is the mature gametophytic stage of fern called

prothallus

What is the mature sporophytic stage of a fern

the large, visible fern plant. It contains fond (leaves), a rhizome (stem), and roots.

draw the mature sporophytic stage of a fern

sex expression within a flower

male (stamen), female (pistil), or both

sex expression within a plant

male, female, or both

draw a dicot and monocot seed that incldes the anatomical parts: seed coat,cotyledons, radcile, endosperm, hilum, and micropyle

seed def

a ripened ovule containing protective tissue (seed coat), food storage tissue (endosperm), and embryo (baby plant)

what is the hium seed part

region of seed where attachment to mother plant occured

what is this seed part called

what is micropyle

where water is imbibed in the seed for germination

what is a cotyldeon

the seed leaves

what is this structure called

cotyledon

What is the radicle

The first root that emerges from the seed

what is hypocotyl

below te cotyledons

what is epicotyl

above the cotyledons

wat do the stoarge tissue of a seed contain

cotyledons and endosperm

the development of ______ precedes _______ development

storage tissues, embryo

seed coats (testa) are derived from

-integuments of the ovule

-remains of nucellus and endosperm

the seed coat (testa) and contain how many layers

1, 2, or rare 3 layers

parthenocarpy means (latin name)

virgin fruit

parthenocarpy def

development of fruit in the absence of fertilization and hence lacking seed

stenospermocarpy def

genetically programmed (single gene mutation) abortion of embryo early in fruit development by manipulating the ploidy

How are seedless watermelons produced

-by a development called stimulative parthenocarpy.

- treated normal diploid (2x) plants with a chemical, colchicine

-which results in double the normal chromosomes

-then cross a diploid parent (2x) with the tetraploid parent (4x)

-the resulting seed will be triploid (3x)

-The seed is sold to a grower and develops into a triploid plant

-They will be sexually sterile because they have an odd chromosome number, so they can't produce eggs or pollen

-thus, no embryos in the ovule, and cannot produce a seed

if a triploid plant cane make seed how do they produce fruit?

in a field of seedless watermelons, every 10th row wis planted normal, (2x) so a seeded diploid variety is present

what is apomixis

asexual formation of a seed from the maternal tissue of the ovule, (bypassing) the process of fertilization

apomixis embroys are ______ to the mother plant

genetically identical (like a clone)

what is the process of apomixis

1. generation of a cell in the ovule capable of forming an embryo

2. fertilization-independent development of the embryo and seed from that cell (parthenogenesis)

what is the first apomixis type and the steps

adventitious embryony

1. Normal meiosis to form the embryo sac and the haploid egg

2. 1x eggs fertilized to form sexual embryos

3. Some nucellar cells of the ovule will become embryogenic and form 2x embryos identical to the mom

apomixis type: adventitious embryony steps simplified

-single seed with multiple embryos

-one embryo is sexually derived

-additional embryos within same seed are maternally drived and clonal

what is the second apomixis type and def

recurrent apomixis.

embryo sac develops but meiosis doesnt occur and embryo devlops

a plant that demonstrates adventitious embryony

mango

a plant that demonstrates recurrent apomixis

no pollination: allium (onion) and dandelions

with pollination: Malus (apple), Rudbeckia, raspberry

a plant that demonstrates vegetative apomixis

onion, venus fly trap

what is the third type of apomixis and def

-nonrecurrent apomixis (rare)

-embryo sac devlops, meiosis occurs and embryo develops

what is the fourth type of apomixis and def

vegetative apomixis

production og vegetative structure other than embryos

vegetative buds or bulbils are produced in the inflorescence in place of flowers

why is apomixis important

ensures uniformity in seed propagation

gets rid of viruses on old clones (seeds dont transmit viruses)

what is primary dormancy

The seed will not germinate even when environmental conditions (water, temp, ad air) are permissive for germination

vivipary latin meaning

bearing live young

what is vivipary

germination of the seed while it is still attached to the parent plant

why are viviparous seeds able to germinate in mother plant

Viviparous mutations lack the ability to synthesize or perceive the hormone abscisic acid (ABA)

(different to dormancy because it is prevented by controlling mechanisms within the seed coat)

what is secondary dormancy

induced under favorable conditions and may further delay germination

-when a seed enters a state of dormancy after it has been dispersed, typically due to unfavorable environmental conditions such as high temperatures, lack of light, or poor oxygen levels

what are quiescent seeds

seeds that are physiologically capable of germination (non-dormant), but fail to germinate because of unfavorable enviro. conditons

what are advanatges of dormancy

-Timing ensures seedling survival

-creation of a seed bank

-synchronization of germination

-facilitates seed disperal

what is a polymorphic seed

taxa that produced durit containing two or more morphologically different (polymorphic) seeds with different dormacy mechanisms

what are the five categories of primary seed dormancy

physical (exogenus dormany)

physiclougcal dorayc

morphological dormancy

morphophysiological dormancy

combinational dormancy

what is the first primary seed dormacy and def

physical (exogenous) dormancy

-hard impermeable seed covering that prevents entrance of water

-scarification

what are the three types of physicological dormancy

non deep

deep

epicotyl

what is nondeep physiological dormancy

embryos excised froms seeds produce normal seedlings

found in many manuals, binennals and some herbaceous perennials

how to overcome non deep physiclofual dormany

prolonged dry seed storage, short chilling exposure or GA treatemnt

what is deep physioloigcal dormany

disapeersonly after 3-4 months of prolonged cool, moist, startification

dormany cannot be covercome by GA

how to overcome deep pysicological dormancy

-startification

-Presoak seed overnight orior to placement in cool stratification

-seed must be hydrated to facilitate successful cool stratifctaion

what is startification

seed exposed to moist cool temo for a period of time

what happens if temperature isnt regulated for seed germ

lack of germination

physiological dwarfing: germination occurs bur seedlings malformed

epicotyl physiological dormany type 1

Radicle develops in autium, following seed dispersal; however, epicotyl development only occurs after moist chilling

epicotyl phsiological dormany type 2

Moist chilling during the first winter following seed dispersal is necessary for radicle development the following spring

Then, the next period of moist chilling after summer will get epicotyl development

explain morpholoigcal dormancy

embryo development is not complete when the seed is shed

undevloped embryos

no chemical dormancy

how to overcome morphological dormancy

exposure to temperatures less than 60°F

exposure to alternating temps

treatment with potassium nitrate or GA

morphophysiological dormancy

morphological + physiological

-embryos underdeveloped at the time of dispersal

-embryos contain biochemical inhibitors that prevent germination

how to overcome morphophysiological dormancy

-The embryo must increase in size before germination can occur

-seed exposed to warm, moist stratification for 1-3 months to facilitate the development of the embryo

-The seed must be exposed to cool, moist stratification for 3-4 months

-Drying is often harmful to these seeds

what is combinational dormancy

-two dormancy mechanisms (physiological and physiological) are operative in the same seed

-hard seed coat (physical) and deep chemical dormancy (physiological)

how to overcome combinational dormancy

1st: scarification of seed coat

2nd: cool, moist stratification