1. Plant Taxonomy: How Plants Are Named
Unit 2
Plant Taxonomy: How Plants Are Named

2. Why are scientific names written in Latin?
The early scholars always wrote in Latin or Greek
Caused problems because the names were often long and difficult.

3. Common vs. Scientific
Most plants have more than one common name. (Common names can be confusing.)
The Swedish botanist, Linnaeus, developed the binomial (two name) system for naming plants.
All plants having the same generic name are said to belong to the same genus and have similar characteristics.
The first name is the genus (plant group name) and the second the species (or kind)
The genus name is usually a noun and the species an adjective

4. Plant Families
Related genera (plural or genus) with similar flower structures are grouped together in major units known as families.

5. The Taxonomist
Scientist who identify and classify plants are known as taxonomists.
An international set of rules drawn up to ensure that every different species has a different binomial name and that the scientific name assigned to that plant is the oldest binomial name ever used is known as the “International Code of Botanical Nomenclature”

6. Parts of the Plant Most plants are made up of four basic parts: Leaves
Stems
Roots
Flowers (these later become fruit or seeds)

7. Leaves Are the food factory of the plant
They produce all of the food that is used by the plant and stored for later use by the plant or by animals

8. Leaves Come in All Shapes and Sizes!
Needles are actually very narrow leaves
The thorns on a cactus are leaves
Some leaves are flat
Other leaves, like onion leaves, are cylindrical
The shape and size of leaves helps to identify plants

11. Leaf Arrangement
Leaves are arranged in many different patterns and positions:
Alternate
Opposite
Whorled
Simple
Pinnate
Bi-Pinnate
Palmate

12. Leaves on the Outside Parts: - Petiole - Blade - Vein
- Midrib - Margin
Tip
Margin
Midrib

13. Leaf Parts cont. Petiole - leaf stalk
Blade - the larger, usually flat part of the leaf
Midrib - large central vein from which all other leaf veins extend
Veins - form the structural framework
Margins - edges of plant leaves

14. Leaves on the Inside
Leaves have specialized cells that perform very important, very specific tasks.

16. Leaf Cells Epidermis - skin of the leaf Single layer of cells
Chief function: protect the leaf from loosing too much moisture
Guard Cells - open and close a small space or pore on the underside of a leaf called a stoma to allow the leaf to breathe (exchange O2 for CO2) and transpire (or give off moisture)

17. Leaf Cells cont. Chloroplasts Photosynthesis Food making cells
Chlorophyll - green color
Photosynthesis
Process by which chloroplasts make food
The oxygen created is used directly by people and animals
Without O2 there would be no burning, rusting, or rotting

18. 6H2O + 6CO2 ----------> C6H12O6+ 6O2
Photosynthesis
LIGHT
6H2O + 6CO > C6H12O6+ 6O2
Six molecules of water plus six molecules of carbon dioxide in the presence of light produce one molecule of sugar plus six molecules of oxygen

19. Plant Food Food made in the leaves moves down the stem to the roots
It is then used by the plant or stored in the roots or stem as sugar, starch, or protein
The plant is also used as food for people and animals
The leaves are usually the most nutritious part

20. Respiration Plants breathe 24/7 They consume O2 and release CO2
Roots, stems, and leaves all need O2 to grow
Plants produce more O2 during photosynthesis than they consume while breathing

21. Stems Stems have 2 main functions: The movement of materials
Movement of water and minerals from roots up towards the leaves
Movement of manufactured food from the leaves down to the roots
Support of the leaves and reproductive structures
Flowers and fruit or seeds

22. Stems cont. Stems are also used for: Food storage Reproductive methods
Irish Potato
Reproductive methods
Stem cuttings or grafting
Green stems manufacture food just like leaves

23. Stems on the Outside
Lenticels
Breathing pores

24. Stems on the Outside cont.
Bud scale scars
Indicate where a terminal bud has been located
The distance between two scars represents one year of growth
Leaf scars
Show where leaves were attached

25. Unique Stems Irish Potato & Gladiolus Very different stems
Stems are used for food storage and plant reproduction
                            

26. Stems on the Inside In all stems:
Water and minerals travel up the XYLEM
Manufactured food travels down the PHLOEM

27. Dicots
Dicots (2 cotyledons) the xylem and phloem are separated by the cambium
The cambium produces new cells
Grow continually because the cambium builds new xylem and phloem cells
Trees are a perfect example!
Sap = new xylem
Heartwood = old, inactive xylem
Tree bark = old, inactive phloem

29. Monocots One cotyledon (seed leaf) Grasses, corn No outside cambium
Vascular bundles that contain xylem & phloem
Cells don’t increase in number, they grow in size (won’t keep growing like a tree)

31. Monocots vs. Dicots

32. What do we do with Stems? Food Building Materials Asparagus
Irish Potato
Celery
Building Materials
Wood

33. Roots Usually underground – not visible Functions:
Anchor the plant and hold it upright*
Absorb water and minerals from the soil & conduct them to the stem*
Store large quantities of plant food*
Propagate or reproduce in some plants
* = essential to all plants

34. Roots on the Inside Very similar to a stem
Older roots of shrubs & trees have:
Phloem on the outside (old phloem is bark)
Cambium layer
Xylem (wood) on the inside

36. Roots on the Inside Phloem Xylem
Carries manufactured food down to the root for food storage
Xylem
Carries water and minerals up to the stem

38. Roots on the Outside Different from a stem On a stem, the terminal bud
initiates growth
On a root,
the root cap
Root cap continuously makes new cells that protect the root as it pushes into the soil

39. Root External Structure
Behind the root cap are root hairs
Root hairs become side roots that branch out as the root grows older
Absorb moisture and minerals which are conducted up to the larger roots and the stem

40. Roots as Crops Cash crops Carrots Beets Radishes Sweet Potatoes
Sugar Beets - Sugar
Radishes
Sweet Potatoes

41. Root Propagation Plants with tuberous roots:
Dahlia
Peony
Sweet Potato
Are propagated by separating the root clump or by rooting spouts from the root

42. Types of Root Systems
Fibrous Root System vs. Tap Root System

43. Which root system is easier to transplant? Fibrous roots or tap roots?
Answer: Fibrous roots
Why? Because when plants are dug up out of the ground, a greater % of the fibrous roots system is saved.

44. If a root loses to many root hairs while being transplanted, the plant will die.
Larger roots only conduct & store water, nutrients, and food
Root hairs absorb moisture from the ground

45. Flowers, Fruits, & Seeds
Flowers are pretty & contain nectar in order to attract insects
These insects fertilize the flower by pollination
Pollination begins fruit and seed formation
                                

46. Fruits & Seeds
Fruits and seeds are eaten, collected, and spread out by animals and people
This reproduces the plant

48. Seeds Seeds have special devices to ensure propagation
Some seeds are sticky (thistles), some float in the wind (dandelions), others can survive stomach acid (cherry pits)

49. Flower Parts
Flowers differ in shape, size, and color, but all have relatively the same parts

50. Flower Parts cont.
Seeds are the most common way plants reproduce in nature
Sexual process involving male and female parents
A complete flower has both male and female parts
Only one parent is needed if a plant is self-fruitful, or can pollinate itself

51. Flower Parts cont.
4 main parts
Sepals
Petals
Stamens
Pistil

52. The Sepals
Green, leaf like parts of the flower that cover and protect the flower bud before it is open

53. Petals Are actually leaves
Generally the most striking part of the flower
Bright colors are used to attract insects for pollination

54. The Stamens Male reproductive part Each stamen consists of: Filament
Anther – contains the pollen (male sex cell)

56. The Pistil Located in the center of the flower Female part
Produces female sex cells (eggs or ovules)
If fertilized, the eggs become seeds

57. Parts of the Pistil 3 main parts: Stigma – sticky, catches the pollen
Style – tube that leads to the ovary
Ovary – eggs develop here, after fertilization the ovary grows to become a fruit or seed coat

59. Flower Construction
Insects looking for nectar have to climb over the anther and brush pollen on their legs
As they climb towards the center looking for food, they deposit pollen on the stigma

60. Fertilization After an insect deposits pollen, fertilization begins!
The pollen grain sprouts and sends
a long stalk (pollen tube) down
the style to the ovary

61. Fertilization cont.
The pollen sperm cell can then fertilize the female egg cells and seeds begin to develop
The ovary enlarges into a seed coat or fruit

62. Incomplete Flower Has ONLY male parts or female parts
Male flower – sepals, petals & stamens but no pistil
Female flower – sepals, petals, & pistil, but no stamens
Examples: Kiwi, Ginkgo

63. Flowers are Important! Many plants are grown only for their flowers
Floriculture industry in a multimillion dollar business!!!