Plant Biology Lecture 3- Plant Morphology I

what is morphology

the external shapes and arrangement of the parts of an organism

what is the largest group of plants that covers 90% of all land plants

angiosperms

what do angiosperms do

1. underpins almost all terrestrial habitats on earth

2. helps to shape ecosystems and build global climates

3. comprises a majority of plant-based food we consume

what are cotyledons

seed leaves that act as an initial source of energy for plant seeds

what are cotyledon scars

scars on angiosperm stems that occur when cotyledons are used up and wither away

what are simple leaves

leaves that are not subdivided. They come off the stem directly across from one another and exhibit opposite phyllotaxy

what are compound leaves

leaves divided into several leaflets. Multiple leaflets come from one petiole and exhibit alternate phyllotaxy

what are nodes

any place where a leaf comes off a stem

what are internodes

the area of stem in between the nodes

what is a leaf axil

angled area where the petiole meets the stem

• the axil of every leaf will have an axillary bud

what are the apices

roto and shoot apex. The primary growing points for plants, where new tissue and organs develop

What is Meristem

exists in root + shoot apex. the primary growth points in plants

• produced new organs/tissues through phytomers

what is a phytomer

consists of a node, a leaf, the axillary bud, and an internode

• As internode extends, shoot apex produces a new phytomer that gets pushed up

what are root hairs

small fuzzy bits that branch off from roots. increases the surface area of roots to help with absorption of water and mineral uptake

what are the reproductive structures of flowers

carpels and stamens

what are carpels

female reproductive structure

• where egg cells are produced

what are stamens

male reproductive structure

• creates polled that carried male gamete

what makes up the perianth

sepals and petals

what are sepals

outer layer of the flower tat protects the developing flower bud

what is a receptable

where the four whorls of a flower develop and emerge from

what is the filament

where the anthers sit on. can be different lengths depending on the plant adaptations and lifestyle

what are anthers

Structure where pollen is produced (that carries male gametes)

• if a plant self-pollinates, anthers will be closer to stigma so the pollen moves to the ovary easier

• if a plant doesn’t self-pollinate, anthers may be higher so the pollen can be easily picked up by pollinators

why are the four plant whorls heavily modified depending on plant

to create floral diversity and help maximisereproductive success

how many floral organs do dicot species have

multiple of 4 or 5

how many floral organs do monocot species have

often multiples of 3

• monocot flowers often appear to not have sepals because the sepals and petals are not differentiated, and look identical

• there are in fact three petals and three sepals

what is it called when the perianth (sepals and petals) are not differentiated

tepals