1. Botany for Master Gardeners
Kim Conway
Texas AgriLife Extension

2. Naming Plants Carl Linneaus (1707-1778) Binomial nomenclature
Based on flower parts
Family
Genus
Species
Binomial nomenclature - scientific system of giving a double name to plants and animals. The first, or genus name, is followed by a descriptive or species name.
Carl Linnaeus
History - leaf shape, plant size, flower color, etc. None of these systems proved workable.
Plant Families

3. Plant Categories Angiosperms Gymnosperms Monocots Dicots Conifers
In order to gain a working knowledge of horticulture, it is necessary to understand the structure and function of plants. In general, flowering plants have certain structures and functions in common.
Gymnosperms - naked seed
Angiosperms -
monocots
dicots

4. Life Cycles Annuals Biennials Perennials herbaceous woody (PG 8)
In addition to being classified as angiosperm or gymnosperm, angiosperms (monocots and dicots), plants are classified by the number of growing seasons required to complete a life cycle.
Annuals pass through their entire life cycle from seed germination to seed production in one growing season and then die.
Biennials are plants which start from seeds and produce vegetative structures and food storage organs the first season. During the first winter a hardy evergreen rosette of basal leaves persists. During the second season flowers, fruit, and seeds develop to complete the life cycle. The plant then dies. (Onions & Pineapples)
Bolting - biennials complete their life cycle in one season.
Perennial plants live for many years, and after reaching maturity, typically produce flowers and seeds each year. Perennials are classified as herbaceous if the top dies back to the ground each winter and new stems grow from the roots each spring. They are classified as woody if the top persists, as in shrubs or trees.

5. Plant Parts & Functions
Sexual
flower
Asexual
leaves
stems
roots
Sexual Reproductive parts
Flower buds, flowers, fruits, seeds
Vegetative parts.
Leaves, roots, leaf buds, and stems.

6. Roots
Primary Roots
Taproot
Lateral Roots
Fibrous

7. Roots Knees Aerial Buttressed
Primary - the root originating during seedling germination
Taproot - occurs whenn the primary root continues to elongate.
Lateral roots - a root that branches off another root.
Fibrous root system - no taproot - just a mass of lateral roots.
Plants that have their taproots cut will form a lateral root system. Interestingly, this is often done commercially in nurseries so that trees which naturally have tap roots will develop fibrous root systems - making it easier to transplant.
Interesting root variations
Cypress knees
Buttressed roots
Aerial roots
Plant spacing
Root develop laterally and usually extend far beyond the spread of branches.

8. Tuberous Roots No Nodes
Some plants produce a modified stem that is referred to as a tuberous stem. Examples are tuberous begonia and cyclamen. The stem is shortened, flattened, enlarged, and underground. Buds and shoots arise from the crown and fibrous roots are found on the bottom of the tuberous stem.
Tuberous root - (dahlia and the sweet potato) produce an underground storage organ called a tuberous root, which is often confused with bulbs and tubers. However, these are roots, not stems, and have neither nodes nor internodes.

9. Root Structure epidermis phloem root hair pericycle endodermis
Meristem - cell maurfacturing
Zone of Elongation - cell size increase
Maturation Zone - cell differentiation
Casparian Strip -
Root Cap - tip of root - cells are shed as the root pushes through the soil
Root Hairs - nutrient and water absorption
casparian strip
meristem
rootcap

10. Dicot Root

11. Monocot Root

12. Stems Support Vascular System Buds Leaves Leaf Bud Flower Bud Terminal
Lateral/Axillary
Adventitious
Leaves
Support (support buds and leaves)
Vascular System - conduits for carrying water, minerals, and sugars (support)
Xylem vessels conduct water and minerals
Phloem tubes conduct food
All stems must have buds or leaves present to be classified as stem tissue
Buds - an undeveloped shoot from which embryonic leaves or flower parts arise
Temperature - May require a certain number of days below a critical temperature (rest) before they will resume growth in the spring.
Leaf Bud - a short stem with embryonic leaves, with bud primordia in the axils and at the apex. Develop into leafy shoots. Less plump and more pointed than flower buds.
Flower Bud - a short stem with embryonic flower parts.
Terminal - are located at the apex of a stem
Lateral/Axilary Lateral buds are borne on the sides of the stem. Most lateral buds arise in the axis of a leaf and are called axillary buds.
Adventitious - at sites other than in the terminal or axillary position. May develop from the internode of the stem; at the edge of a leaf blade; from callus tissue at the cut end of a stem or root; or laterally from the roots of a plant.
Leaves
Node - An area of the stem where leaves are located Nodes are areas of great cellular activity and growth, where auxiliary buds develop into leaves or flowers.
Internode - the area between nodes
length - etiolation. Growth produced early in the season has the greatest internode length. Internode length decreases as the growing season nears its end.

13. Meristems Primary Growth Secondary Growth apical meristem or apex
Vascular cambium or cambium
Meristems - a site of cell division and active growth.
The cambium is a meristem. It is located between the xylem and phloem inside the bark of a stem and is the tissue responsible for a stem’s increase in girth, as it produces both the xylem and phloem tissues.

14. Primary Growth - Monocot
epidermis
vascular bundle
phloem
xylem
bundle sheath
The three major internal parts of a stem are the xylem, phloem, and cambium.
The vascular systems of monocots and dicots differ. While both contain xylem and phloem, they are arranged differently. In the stem of a monocot, the xylem and phloem are paired into bundles; these bundles are dispersed throughout the stem.

15. Monocot Stem

16. Primary Growth – dicot or gymnosperm
cortex
epidermis
pith
phloem
In the stem of a dicot, the vascular system forms rings inside the stem.
xylem

17. Dicot Stem

18. Secondary Growth - dicots
periderm
phloem
cambium
xylem 1
pith 2
ray 3
The ring of phloem is near the bark or external cover of the stem and is a component of the bark in mature stems. The xylem forms the inner ring; it is the sapwood and heartwood in woody plants. The difference in the vascular system of the two groups is of practical interest to the horticulturist because certain herbicides are specific to either monocots or dicots. An example is 2, 4, -D, which only kills dicots.
crushed cortex and past year’s phloem

19. Modified Stems - Crowns & Stolons
Although typical stems are above-ground trunks and branches, there are modified stems which can be found above ground and below ground. The above-ground modified stems are crowns, stolons, and spurs, and the below-ground stems are bulbs, corms, rhizomes, and tubers.
Crown - are compressed stems having leaves and flowers on short internodes, generally found near the surface of the soil. Crowns (strawberries, dandelions, African violets).
Stolon - horizontal stem that is fleshy or semi-woody and lies along the top of the ground. A runner is a type of stolon. It is a specialized stem that grows on the soil surface and forms a new plant at one or more of its nodes. Strawberry runners are examples of stolons.
Remember, all stems have nodes and buds or leaves. The leaves on strawberry runners are small but are located at the nodes which are easy to see. The spider plant also has stolons.

20. Modified Stems - Spurs
Spur - a compressed fruiting branch. Spurs are short, stubby, side stems that arise from the main stem (pears, apples, and cherries). If severe pruning is done close to fruit-bearing spurs, the spurs can revert to a long, nonfruiting stem.

21. Modified Stems Bulb Corm Tuber Bulb Rhizome
Tuber - an enlarged portion of an underground stem. (potato tubers, tulip bulbs, and iris rhizomes) Potato eyes are nodes - any piece of a potato with an eye will produce a new plants
Rhizomes - a specialized stem growing horizontally at or just below the soil surface that can be divided into pieces. Storage organs - (iris, bentgrass)
Bulbs - shortened compressed underground stem surrounded by fleshy scales (leaves). form small bulblets at the base of the parent bulb. If you cut through the center of a tulip or daffodil bulb in November, you can see all the flower parts in miniature within the bulb. Many bulbs require a period of low-temperature exposure before they begin to send up the new plant.
Corms - similar to bulbs with no fleshy scales. They form cormels are miniature corms that form under the parent corm.
Rhizome

22. Types of Leaves Scale leaves Seed leaves Spines Thorns Tendrils
Brachts
Needles
Simple
The principal function of leaves is to absorb sunlight for the manufacturing of plant sugars in a process called photosynthesis. Leaves develop as a flattened surface in order to present a large area for efficient absorption of light energy.
The blade of a leaf is the expanded, thin structure on either side of the midrib.
Petiole - the stalk which supports the leaf blade. The base of the petiole is attached to the stem at the node. It varies in length and may be lacking entirely in some cases where the leaf blade is described as sessile.
Axil - The small angle formed between the petiole and the stem.
Stipule -an active or dormant bud or cluster of buds is usually located in the axil.
Types of leaves
Scale leaves or cataphylls are found on rhizomes and are also the small, leathery, protective leaves which enclose and protect buds.
Seed leaves, or cotyledons, are modified leaves which are found on the embryonic plant and commonly serve as storage organs.
Spines and tendrils, as found on barberry and pea, are specialized modified leaves which protect the plant or assist in supporting the stems.
Storage leaves, as are found in bulbous plants and succulents, serve as food storage organs. Other specialized leaves include
Bracts, which are often brightly colored. The showy structures on bougainvillea and poinsettias are bracts, not petals.
Conifers, (pines, firs, spruce, laurel, etc.) have "needles" as leaves.

23. Leaves
Absorb
sunlight
for photosynthesis

24. Leaf Layers The leaf blade is composed of several layers.
Epidermis top and bottom is a layer of thickened, tough cells called the. The primary function of the epidermis is protection of leaf tissue. The way in which the cells in the epidermis are arranged determines the texture of the leaf surface. Some leaves have hairs that are an extension of certain cells of the epidermis. The African violet has so many hairs that the leaf feels like velvet.
Part of the epidermis is the cuticle, which is composed of a waxy substance called cutin that protects the leaf from dehydration and prevents penetration of some diseases. The amount of cutin is a direct response to sunlight, increasing with increasing light intensity. For this reason, plants grown in the shade should be moved into full sunlight gradually, over a period of a few weeks, to allow the cutin layer to increase and to protect the leaves from the shock of rapid water loss or sun scald. The waxy cutin also repels water and can shed pesticides if spreader-sticker agents or soaps are not used. This is the reason many pesticide manufacturers include some sort of spray additive to adhere to or penetrate the cuticle.
Some epidermal cells are capable of opening and closing. These cells guard the interior of the leaf and regulate the passage of water, oxygen, and carbon dioxide through the leaf. These regulatory cells are called guard cells. They protect openings in the leaf surface called stoma. The opening and closing of the cells are determined by the weather. Conditions that would cause large water losses from plants (high temperature, low humidity) stimulate guard cells to close. Mild weather conditions leave guard cells in an open condition. Guard cells will close in the absence of light. A large percentage of stomata occur in the lower epidermis.
The middle layer of the leaf is the mesophyll and is located between the upper and lower epidermis. This is the layer in which photosynthesis occurs. The mesophyll is divided into a dense upper layer, called the palisade layer, and a spongy lower layer that contains a great deal of air space, called the spongy mesophyll. The cells in these two layers contain chloroplasts which are the actual sites of the photosynthetic process.

27. Stomates

28. Parallel Pinnate Palmate Leaf Venation Vascular bundles
Net veined - primarily dicots. This enmeshed system is more resistant to tearing than parallel-veined leaves.
palmate - fanned
pinnate - principally extend from midrib
Parallel - primarily monocots
run parallel to each other
connected to one another by tiny veinlets

29. Double Pinnate Compound Pinnate Compound Palmate Compound Simple
Leaf Types
Simple
Compound - individual leaflets
Three types of compound
palmate - chifflera
pinnate compound - locust, roses, palms, legumes
double pinnate - honeylocust

30. Leaf Shapes Linear Ovate Cordate Lanceolate Elliptical
Although we classify plants by their reproductive parts - we describe plants using specified terms for leaf shapes (apex and base) margins and arrangements. A few common leaf shapes are shown here. It’s important not so much that you memorize these shapes and their names, but know they exist, so that when you are attempting to identify a plant from a plant key or a written description, you can look up the terms and know if the plant you are looking at meets the criteria in the description.

31. Leaf Types

32. Leaf Margins Entire Sinuate Crenate Dentate Serrate Incised Lobed
Cleft
The various ways leaves are arrange along a stem are also used to help identify Entire
Sinuate
Crenate
Dentate
Serrate
Incised
Lobed
Cleft

33. Leave Arrangement alternate opposite whorled whorled alternate
rosulate - basal leaves

34. Sexual Plant Parts & Functions
(Flowers)

35. { } Parts of the Flower Petal Pistil Stamen Sepal Ovule Receptacle
Anther
Filament
Sepal
Ovule
Receptacle
Stigma
Style
Ovary }
Stamen {
Pistil
The sole purpose of the flower is reproduction.
Fragrance, color etc attract pollinators.

36. Types of Flowering Plants
Monoecious = 1 House
Corn
Pecan
Dioecious = 2 Houses
Holly
Junipers

37. Flowers Complete = Pistil, Stamen, Petal, Sepals
Incomplete = Missing One
Perfect = Pistil & Stamen
Monoecious - one house
Dioecious - two houses
Complete - stamen, pistil, petal, sepal
Incomplete - missing any one part
Perfect - contains stamen and pistils

39. How Seeds Form Pollination Pollen tube Fertilization
Pollen Germination
Pollination
Pollen tube
Fertilization
Growth of Pollen Tube toward Ovule
Pollination
Pollen tube
Fertilization

40. Solitary - one flower per stem Inflorescence - a cluster of flowers
Types of Flowers
Solitary - one flower per stem
Inflorescence - a cluster of flowers
racemous - indeterminate (flower from the bottom up)

41. Racemous Flowers
Spike - flowers attached to peduncle - gladiolus

42. Raceme - individual flowers attached by tiny stems to the peduncle
Racemous Flowers
Raceme - individual flowers attached by tiny stems to the peduncle
Bluebonnet

43. Racemous Flowers
Catkin
Mulberry
birch

44. Racemous Flowers
Corymb
yarrow

45. Racemous Flowers
Umbel –
dill,
onion
queen anne’s lace

46. Racemous Flowers
Head –
sunflower
daisy

47. cyme - determinate - flower from the top down - top florets open first
Flower Types
cyme - determinate - flower from the top down - top florets open first
dischasium cyme - baby’s breath
helicoid cyme - freesia
scorpioid - tomato (alternate)

48. Types of Inflorescence
Solitary - one flower per stem
Inflorescence - a cluster of flowers
racemous - indeterminate (flower from the bottom up)
spike - flowers attached to peduncle - gladiolus
raceme - individual flowers attached by tiny stems to the peducle - blue bonnet
catkin - mulberry
corymb - yarrow
umbel - dill, onion, queen anne’s lace
head - sunflower, daisy
cyme - determinate - flower from the top down - top florets open first
dischasium cyme - baby’s breath
helicoid cyme - freesia
scorpioid - tomato (alternate)

49. Fruit
Fruit consists of the fertilized and mature ovules (seeds) and the ovary wall.

50. Parts of the Fruit exocarp mesocarp pericarp endocarp seed dry fruit
(corn)
fleshy fruit (peach)
exocarp
mesocarp
endocarp
pericarp
Seeds - fertilized and mature ovules (genetically representative of the male and female)
Ovary wall - fleshy (apple) hard - maple
Seeds can be inside the ovary (apple, orange etc) - or - Outside - strawberry, corn, sunflower)

51. Types of Fruit drupe Berry pod Pepo aggregate Pome multiple
Hesperidium
Simple - develop from a single ovary - drupe (cherry, peach), pome, berries
berry
pepo
pome
hesperidium
drupe
pod
aggregate - single flower with many ovaries
multiple - tight cluster of separate but individual flowers (pineapple

52. Parts of the Seed testa (seed coat) hilum micropyle dicot seed (bean)
plumule
epicotyl
cotyledon
hypocotyl
radicle
embryo
Embryo
plumule - petiole
epicotyl - stem
cotyledon - leaf
hypocotyl - root
radicle - root tip
Seed Coat (testa) - protection
Hilum - Belly button
Micropyle - hole for water absorption
Endosperm - built in food supply made up of proteins, carbs or fat

53. Seed Germination Water Light Heat Oxygen
Germination is the resumption of active embryo growth.
Water absorbed
Proper environmental conditions: oxygen, temperature (light)
Radicle first - it becomes the primary root
Development of primary root and lateral roots
Hypocotyl etc.

54. The End