bsc2011l : angiosperm practical review

Angiosperms (Anthophyta)

- flowering plants

- lack antheridia and archegonia bc reduction of m/f gametophytes

- 2 integuments around embryo

- protected/covered seeds; have fruits

- double fertilization

- 3n endosperm

parts of a flower

- stamen

- pistil

- sepal

- petals

calyx

made of whorls of sepals

corolla

all petals

stamen

Male part of the flower; made up of an anther and a filament.

- in a complete flower, it surrounds the pistil (the female pt of the flower)

filament

Supports the anther

anther

the part of a stamen that contains the pollen.

- microsporogenesis occurs inside anther

microsporogenesis

meiotic divisions producing pollen in anther

microgametophyte

pollen

- in angiosperms, typically consists of only 3 cells

pistil aka carpel

female part of the flower; ovary, style and stigma

carpel

The female reproductive organ of a flower, consisting of the stigma, style, and ovary.

- individual segments of an ovary that are fused 2gether; often not fused completely; styles most often are unfused & # of carpels making up pistil can easily be counted

flowers w/ both male and female reproductive structures...

self-pollination & fertilization is uncommon

- stamens & pistils on a single flower tend to mature @ diff times

- anthers are exposed & release pollen 1st

- l8r, stigma and style mature & are receptive to pollen de otra flowers

flower ovary

the female reproductive organ on flowers that hold ovules and become fruit in some plants/trees

megaspore mother cell

in angiosperms, this divides by meiosis to form 4 haploid *megaspores*

- 2n

- this large cell with 8 nuclei is the female gametophyte, called the *embryo sac*

megaspores

develop into female gametophytes

- 4 are produced

- 3 nuclei will fuse together, forming 1 3n nucleus

- it then undergoes 2 mitotic divisions in sequence, generating 4 triploid nuclei

- 3 of these form antipodal nuclei

- other migrates to center of the embryo sac and becomes polar nuclei

- remaining haploid nucelus from the initial meiotic division undergoes 2 rounds of mitotic cell divisions, making 2 synergids (n) & 1 haploid polar nucleus

- resulting megagametophyte has 7 cells, 8 nuclei; 4 n & 4 2n.

embryo sac

female megagametophyte; develops from the 2n megaspore mother cell within the ovule

primarily haploid

megagametophyte

ovule

- surrounded by 2 integuments

micropyle

opening between the integuments

integument

tissue from the sporophyte that acts as the seed coat

double fertilization

sexual reproduct.

- pollination @ stigma - germination - pollen tube grows down thru style - tube has 3 nuclei, a pollen tube nucleus, & 2 sperm nuclei - pollen tube grows into ovary to an ovule - pollen tube grows to reach embryo sac thru the micropyle - mycropyle closes after fertilization

- 1 sperm fertilizes egg, 1 - 2n zygote - embryo

- other sperm fertilizes polar nuclei to forming a pentaploid(Lilium), but angiosperms usually have a 3n endosperm

stigma

site of pollination; where pollen is deposited

endosperm

3n nutritive tissue utilized by the growing embryo

seed

mature ovule w/ 2 integuments

fruit

mature ovary, contains the ovules

monocots

- advanced clade of angiosperms

- 1 cotyledon

- parallel veined

- fibrous/adventitious roots

- unorganized/scattered vascular bundle

- monosculate pollen; 1 aperature

- flowers in grps of 3

eudicots

- 2 cotyledons

- tricolpate; 3 germination apertures in pollen

- net-veined leaves

- flowers in grps of 4 or 5

- tap-root

- circular vascular bundle

parallel venation

veins running parallel to one another along or across the leaf surface

reticular venation

netlike pattern of branching

magnoliids & eudicots

primary roots

taproots; 1 main root w/ many lateral filaments

- eudicots and magnoliids

adventitious roots

bunches of fine, fibrous root filaments

- monocots

vascular tissue

xylem and phloem

xylem

transport h2o & dissolved minerals

-composed of vessels and or tracheids

- dead tissue - only cell walls remain

phloem

transport sugar/sucrose

- composed primarily of sieve tube cells

- living tissue

cortex angiosperm

ground tissue between vascular elements and the epidermis

primary growth

growth in length

- produced by apical meristems

secondary growth

Growth produced by lateral meristems, grow in diameter

- result of vascular cambium & may also be bc of cork cambium

vascular cambium

produces secondary xylem and phloem

2ndary growth

cork cambium

located in cortex outside of phloem tissue; lateral growth by forming outerbark/cork

Scelerenchyma

thick-walled cells important in support

Collenchyma

a modified form of parenchyma specialized for support in young plant organs

apical meristem

tips of roots and shoots

primary growth

axillary buds

at base of leaves

node

site where leaves & buds emerge

plant body parts

shoot, leaves, root

buds

undeveloped shoots; may form flowers, leaves, or new lateral shoots

vascular bundle arrangement

inner to outer;

- pith

- xylem

- vascular cambium

- phloem

- sclerenchyma on outer edge of phloem

- collenchyma cells surround the top of ea of the vascular bundles

- epidermis = outermost cell layer

pith

lrg, thin-walled cells @ center of stem

spring xylem

vessels/rings produced during active growth in the early pt of the season

- lrgr diameters (outer rings)

summer xylem

vessels produced l8r in the season; narrower

phloem rays

light-colored, triangular

xylem rays

are associates w/ phloem rays; responsible for the lateral transport of food materials in the stem

lower epidermis

contains stomata; have air spaces w/in spongy mesophyll

guard cells

regulate the opening & closing of the aperature

spongy mesophyll

spongy layer found beneath the palisade mesophyll in a leaf

- gas exchange lrgly occurs across the spongy mesophyll

upper epidermis

the part of the leaf above the palisades layer; coated by cuticle

palisade mesophyll

elongated cells under the upper epidermis of a leaf; primary sites of photosynthesis w/in leaf

simple leaves

single blade

complex leaves

composed of a # of leaflets

axillary bud found on bottom of leaf

palmate

A leaf vein pattern in which there are several veins that all start at one point near the base. The veins look like the fingers of a hand

pinnate leaf

a leaf that is similar to a feather because the veins all stem from one major vein that goes straight up the middle

roots

store photosynthate in the cortex in the form of starch; anchors the plant in the substrate and abosrbs h2o & dissolved minerals de the surrounding environment