© Project SOUND

Out of the Wilds and Into Your Garden

Gardening with Western L.A. County Native Plants Project SOUND – 2012 (our 8th year)

© Project SOUND

Botany for S. CA

Gardeners Key Botanic Concepts to

Improve Your Gardening

C.M. Vadheim and T. Drake

CSUDH & Madrona Marsh Preserve

Madrona Marsh Preserve

February 1 & 4, 2014

California – the land of extremes

Latitude

Elevation

Temperature

Precipitation

Soil type, content

© Project SOUND

That’s part of the reason why

my have so many unique

native plants

http://mapsof.net/uploads/static-maps/california_relief_map.png

Botany: the study of plants (huge subject area)

I. Names, descriptions and taxonomy

II. Seeds A. How they develop

B. Dispersal

C. Germination

III.How plants grow

IV. Water & nutrients from the environment

© Project SOUND

Today’s talk

© Project SOUND

Hollyleaf Redberry – Rhamnus ilicifolia

© 2003 BonTerra Consulting

Scientific names: why do we need ‘em?

They are (or at least should be) universal

They are unique to a given taxon – unlike common names like ‘Wild pea’ or ‘Wild sunflower’

The name sometimes describes characteristics of the plants [ilicifolia = holly-like leaves] or honors the person who discovered them

The name (should) reflect the evolutionary relationships between it and other taxa

© Project SOUND

Rhamnus ilicifolia

© 2006 Steve Matson

Taxonomy & Systematics: grouping & naming

Taxonomy: science that finds, identifies, describes, classifies, and names plants

Three goals:

Identification : identifying an unknown plant by comparison with previously collected

Classification: placing known plants into groups or categories to show some relationship.

Description : formal description of a new species, usually in the form of a scientific paper

Systematics: the science of relationships between plants and their evolution, especially at the higher levels

Classical (morphological) systematics – based on similarities in plant physical characteristics (how plant looks; chemical similarities; etc.)

Molecular systematics – based on similarities in genetic material

© Project SOUND

The two are highly interrelated – both aim to better understand and

reflect the true relationships between different plants

© Project SOUND

Kingdom Plantae – Plants Subkingdom Tracheobionta – Vascular plants Superdivision Spermatophyta – Seed plants Division Magnoliophyta – Flowering plants Class Magnoliopsida – Dicotyledons Subclass Rosidae Order Rhamnales Family Rhamnaceae – Buckthorn family Genus Rhamnus L. – Buckthorn Species Rhamnus ilicifolia Kellogg – Hollyleaf redberrry

© 2005 James M. Andre http://seinet.asu.edu/images/vasc_herbarium_images/Rhamnaceae/photos/Rham_croc_SL_N0086.jpg

Resources to help the confused gardener

USDA Plants Database: http://plants.usda.gov/java/

© Project SOUND

The importance of higher taxa: insight

Family Rhamnaceae

Mostly trees/shrubs

Simple leaves, with stipules

Flowers usually small, inconspicuous [exception: Ceanothus spp.]

Fruits are mostly berries, fleshy drupes or nuts – mostly dispersed by mammals and birds.

Chiefly used as ornamental plants and as the source of many brilliant green and yellow dyes

© Project SOUND © 2003 BonTerra Consulting

© 2005 James M. Andre

The importance of higher taxa: insight

Genus Rhamnus Common name: Buckthorn

Usually deciduous – CA has evergreen species

Fruit: berrylike, fleshy (edible?)

Wide light tolerance range

Generally drought tolerant once established

May be slow to get started – then easy to grow

May cause mild dermatitis

Medicinal: prepared bark - purgative; laxative

Invasive potential: in Eastern U.S., exotic buckthorns (R cathartica; R. frangula) tend to form dense, even-aged thickets, crowding and shading out native shrubs and herbs

California members: Rhamnus (now Frangula) californica – CA

Coffeeberry

Rhamnus crocea – spiny redberry

© Project SOUND

Spiny redberry

Rhamus crocea

http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.htm

© 2002 Kristiaan Stuart

© Project SOUND

The scientific name

The generic name is listed first (with its first letter capitalized), followed by a second term, the specific name (or specific epithet) and the name(s) of the first namer

International Code of Botanical Nomenclature – specifies the format and conventions

U.S. Integrated Taxonomic Information System (ITIS) - facilitates sharing biologic info. by providing a common framework for taxonomic data

Sometimes regional experts don’t agree with ITIS

Hollyleaf redberry Rhamnus ilicifolia Kellogg

Calflora database: CA plants (native & not)

© Project SOUND

© Project SOUND

What is a species?

Some definitions of species

Biological Species Concept - they cannot interbreed & produce viable offspring; interbreeding studies

Morphospecies Concept - they are different morphologically and do not come in contact for interbreeding

Genetic Species Concept – still working on this – how similar must they be to constitute a species?

Practical definition - Practically, biologists define species as populations of organisms that have a high level of genetic similarity.

The field of taxonomy is changing with our increasingly sophisticated tools

Lyonothamnus floribundus

ssp. aspleniifolius

Lyonothamnus floribundus

ssp. floribundus

California (and other biologic ‘hotspots’)

present more challenges

Lots of geographic/topographic variability

Relatively ‘rapid’ environmental changes (since last Ice Age)

Lots of geographically separate populations – are in the process of diverging

In other words, speciation is a ‘work in progress’

© Project SOUND

© 2002 Kristiaan Stuart

http://biology.csusb.edu/PlantGuideFolder/RhamnusCrocea/RhamnusCroceaPage.ht

m

Rhamnus ilicifolia

Rhamnus crocea

Why all the current taxonomic/systematic

arguments about CA native plants?

When two species have fully diverged from a common ancestor they will possess the properties commonly associated with independent species: reproductive incompatibility

distinctive morphology

ecological uniqueness.

During the process of divergence, these properties are gradually acquired in a continuum spanning thousands of years.

When two lineages are in the early stages of speciation it is difficult for biologists holding different species concepts to agree on when there has been enough divergence to declare them as different species.

© Project SOUND

What’s a CA native plant gardener to do?

Keep calm – this period of rapid change will end

Nurseries will likely know plants by both old and new name

Use on-line sources Native Plants at CSUDH

Scientific name - Scientific name key

Common name - Scientific name key

USDA Plants database

Calflora database

© Project SOUND

http://www.zarachiron.com/2013/06/spanish-men-a-cultural-enigma/

Native Plants at CSUDH - http://nativeplantscsudh.blogspot.com/

© Project SOUND

Use the ‘pages’ on left of screen

© Project SOUND

Name to name lists are here

The PLANTS

database

Implications of plant taxonomy/systematics

for the gardener

Precise, scientific names are important:

For scientists – including biomedical scientists working with plant-based medicinal chemicals, insecticides, etc.

For you as a gardener – so you purchase the plant whose characteristics you want

Plant systematics provides insights

Understanding basic characteristics of groups – requirements, susceptibilities, toxicities

© Project SOUND

© 2002 Kristiaan Stuart

Rhamnus ilicifolia

Implications of plant

taxonomy/systematics for the gardener

Conservation – importance of conserving local endangered species in gardens, seed banks, etc.

Choice of appropriate plant species – esp. if cross-pollination danger [Salvias; Buckwheats]

Evolution in the garden ‘garden-friendly’ cultivars

(including novel hybrids)

Selection and climate change

© Project SOUND

Plant anatomy and morphology:

describing plants

© Project SOUND

Describing plants: what do those terms mean?

Stem: bark gray; branches stiff, generally ascending; twigs glabrous to finely hairy.

Leaf: evergreen; petiole 2–10 mm; blade 20–40 mm, ovate to round, thick, glabrous adaxially, glabrous or hairy, flat to concave abaxially, base rounded, tip obtuse, rounded, or widely notched, margin entire, irregularly toothed, or prickly, veins prominent or not.

© Project SOUND http://www.calflora.net/bloomingplants/hollyleafredberry.html

Describing plants: simple leaves

Basic anatomy Petiole

Blade

Stipule

Veins Midrib

Veins

Shape terminology Overall shape

Blade tip

Blade base

Margins

© Project SOUND

http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm

Margin Blade tip

Base

Simple vs.

compound leaves

Clues:

Look for an axillary bud (just above the midrib)

Look at old (or recently fallen) leaves – the petiole separates cleanly from the branch (due to an abscission layer)

Use plant Family traits – [Pea family (Fabaceae) usually have compound leaves]

© Project SOUND

http://www.robinsonlibrary.com/science/botany/anatomy/leafparts.htm

Describing plants: leaf shapes

© Project SOUND

http://www.clemson.edu/extfor/publications/bul117/characteristics.htm

toothed http://www.nbh.psla.umd.edu/guides/appendix2.html

Describing plants: what do they mean?

Stem: bark gray; branches stiff, generally ascending; twigs glabrous to finely hairy.

Leaf: evergreen; petiole 2–10 mm; blade 20–40 mm, ovate to round, thick, glabrous adaxially, glabrous or hairy, flat to concave abaxially, base rounded, tip obtuse, rounded, or widely notched, margin entire, irregularly toothed, or prickly, veins prominent or not.

© Project SOUND http://www.calflora.net/bloomingplants/hollyleafredberry.html

Botanical terms/concepts & plant identification

Some excellent resources written specifically for the gardener

These 3 books are very good

© Project SOUND

Help with terminology

Books Allaby, M : Oxford Dictionary

of Plant Sciences

Beentje, H : Kew Plant Glossary - an illustrated dictionary of plant terms

On-line: Several good resources – good

for gardeners

© Project SOUND

We’ve tried to make using on-line resources easier by bringing together the best in one place – ‘Native Plants at CSUDH’

Let ‘Native Plants at

CSUDH’ help

© Project SOUND

The ‘Pages’ on the left of the screen provide helpful links to the Project

SOUND/Out of the Wilds plant lists(under ‘Plant Lists’), gardening

information sheets & plant photos (under ‘Gallery of Native Plants’)

Gallery of Native Plants – Native Plants at CSUDH

© Project SOUND

There alphabetical name lists:

• Scientific name to current sci name

• Common name to scientific name

Native Plant Gallery – Native Plants at CSUDH

© Project SOUND

Click ‘Save’ – then choose to download

or save. You’ll be able to click on links

Help make the

‘Gallery’ even better

© Project SOUND

Send us your pictures of CA native

plants growing in garden settings

Native Plants at CSUDH

http://nativeplantscsudh.

blogspot.com/

© Project SOUND

Just search ‘native plants

at csudh’ with your favorite

browser

We’re very familiar with the life stages of

animals

© Project SOUND

http://www.baby-connect.com/

http://onlinebusiness.volusion.com/articles/seniors-online/

http://fastfoodies.org/movie-food/elderly-people-on-computer/

Plants have similar – but different – life stages

Fertilization

Embryogenesis/seed formation

Seed germination/early growth

Juvenile growth (vegetative)

Mature growth (vegetative)

Flowering/Fruiting/seed production

Senescence

Death

http://ww2.valdosta.edu/~ckbeck/ebook.html

Describing plants: what do they mean?

Inflorescence: 1–6-flowered, generally glabrous; pedicel 2–4 mm.

Flower: generally unisexual; hypanthium ± 2 mm wide; sepals 4; petals 0.

Fruit: 2-stoned, 4–8 mm, red.

© Project SOUND

Mark W. Skinner @ USDA-NRCS PLANTS Database

© 2002 Kristiaan Stuart

http://www.researchlearningcenter.org/bloom/species/Rhamnus_ilicifolia.htm

Inflorescence: grouping/arrangement of flowers

© Project SOUND

http://www.flowers-gardens.net/gardens/types-of-inflorescence.html

Wikipedia has a very good coverage of inflorescence terms

Flowers are leaves specialized for reproduction

Calyx (whorl of Sepals) – protect/attract

Corolla (whorl of Petals) – attract

Stamen – male sex parts Filament

Anther – produces pollen

Pistil – female sex parts Stigma – receives pollen

Style – channel

Ovary – contains eggs which become seeds

© Project SOUND

A ‘perfect’ flower – has all the parts

http://scienceblogs.com/pharyngula/2006/11/20/mads-boxes-flower-development/

How does the pollen get to the stigma?

Falls on it

Physical agents Wind

Water

Biologic agents (Mother Nature’s cupids) Bees

Flies

Butterflies/moths

Other insects

Hummingbirds

Bats

Other animals

© Project SOUND

Take-home messages: pollination

Getting the pollen to the egg isn’t easy if you’re a plant – and you usually need a little help

The lives of plants and their pollinators are in intimately intertwined

Plants and animal pollinators have evolved together (co-evolution).

Plants usually don’t waste energy on things they don’t really need – the color/scent etc. are there for a reason

© Project SOUND

What are the likely pollinators of

Hollyleaf redberry?

Pollination and

Fertilization

http://www.educationcaribbean.com/resources/encyclopaedia/science/plants.asp

What does it take to form a seed?

© Project SOUND http://www.bio.miami.edu/dana/226/226F09_4.html

The unwritten goal of all living things:

reproduce and disperse

© Project SOUND

That’s how species survive

through time

Why the need to disperse?

To colonize new areas – which may have better resources or other advantages

To increase genetic diversity within the species or population – novel combinations that may confer an advantage

© Project SOUND

To decrease unhealthy competition (for light, water, other resources)

http://ebd10.ebd.csic.es/ebd10/Dispersal_and_gene_flow_files/shapeimage_2.png

Dispersal is relatively easy if you have

legs or can swim

© Project SOUND http://www.immortalhumans.com/early-man-had-the-same-life-span-as-neanderthals/

Seed dispersal: traveling through space

Dropping to the ground

Catapulted from the dry seed capsule (fruit)

Carried by physical agents Floating on the wind

Carried by water

Carried by living agents Hitchhiking on animal fur, feathers

or feet

Travelling through a bird or animal for eventual deposition

© Project SOUND http://science.psu.edu/news-and-events/2010-news/Carlo2-2010

Clues to dispersal: often easy to read

© Project SOUND

Box Elder – Acer negundo

Jojoba - Simmondsia chinensis

http://www.arizonensis.org/sonoran/places/cavecreek.html

Size/weight

Flight/hitchhiking appendages

Inside a fleshy fruit

Characteristics of pod/capsule

CA poppy

Others are a little more difficult

© Project SOUND

http://www.arizonensis.org/sonoran/places/cavecreek.html

Yellow Paloverde – Parkinsonia microphylla

Pea family Large, heavy seeds

Characteristic pod

Plant distribution in landscape Along seasonal streams

Seeds distributed by water

Effective for dispersing large, heavy seeds over wide area

Ensures that seeds will be dispersed at a time conducive to germination

Ensures that plants grow where best suited to survive

Seed distribution implications for gardeners

Some seeds are born to naturalize: small seeds [annual wildflowers]; wind-born seeds [Milkweeds]

Plant species with fleshy fruits and you’ll attract fruit-eating birds & other dispersal agents

Remember, some seeds are meant to be carried in animal fur (clothing, etc.) [some grasses; cocklebur]

Plants with unusual dispersal mechanisms may require special treatments to encourage them to germinate

© Project SOUND

http://dendro.cnre.vt.edu/dendrology/syllabus/fact

sheet.cfm?ID=491

Yellow Paloverde

Parkinsonia microphylla

A seed is somewhat like a ‘manned’

space capsule

A ‘capsule’ with a protective covering

Containing A living organism: so dry that it’s in a state of suspended

animation

Provisions for the journey & for re-settlement

Traveling through space & time © Project SOUND

http://millburyschools.sharepointsite.com/elmwood/lhippert/Picture%20Library74/Forms/DispForm.aspx?ID=3&RootFol

der=%2Felmwood%2Flhippert%2FPicture%20Library74%2F1 http://www.gijoecanada.com/index.php?main_page=product_info&cPath=71_76_

90&products_id=404

The consequences of seed travel through

time and space

Must have adequate protection – for wide range of possible conditions

Must have adequate provisions

Must provide everything needed to keep the ‘living being’ alive until it reaches it’s final destination

Must keep the weight/size down (usually – depends on dispersal)

Must not open the hatch-door until it’s reached its destination and conditions are ‘favorable’

© Project SOUND http://www.ehow.com/info_8547249_stages-plant-reproduction.html

The mighty seed

© Project SOUND

http://generalhorticulture.tamu.edu/HORT604/LectureSupplMex07/HORT604Mexico2007.htm

Seed coat (testa) – protective coat

Cotyledon/Endosperm - food source

Embryo

Radicle (embryonic root)

Hypocotyl/epicotyl (embryonic root/shoot)

Plumule (embryonic shoot/leaves)

http://www.cmg.colostate.edu/gardennotes/137.html

monocot seed (corn)

Overview of Embryonic Development

http://www.pnas.org/content/107/18/8063/F1.expansion.html

A completely mature, dry seed remains in

a state of suspended animation…

sometimes for a very long time

© Project SOUND

Seed germination: complex process

What we’re interested in today is how does a seed begin the germination process – and what does it need to survive as a seedling

© Project SOUND

Koning, Ross E. 1994. Seeds and Seed Germination. Plant Physiology Information Website. http://carlsbadcommunitygardens.org/2013/04/2nd-annual-carlsbad-seed-swap-at-the-smerdu-community-garden/

You may have noticed that fresh seeds

often germinate more easily

© Project SOUND

…but most seeds don’t

germinate prematurely. Why?

http://viviparouscapsicumfruitescens.blogspot.com/

The timing of germination is critical

Must be adequate resources for the seedling to survive: Water

Light

Nutrients

Possibly other

Must not have future conditions that will kill a young seedling (seedling stage is the most vulnerable life stage): Too low or too high

temperatures

Drought

Fire

© Project SOUND

California poppy - Eschscholzia californica

Immediate

future

Slightly

longer range

Plants have developed several strategies

to prevent premature germination

Seed quiescence : delay germination because the external environmental conditions are not right : too dry or warm or cold for germination [most annuals; many fresh woody plant/perennial seeds]

Seed dormancy : seed is unable to germinate in a specified period of time under environmental conditions that are normally suitable for the germination of the non-dormant seed [many woody plant species normally facing challenging conditions]

© Project SOUND

Several different processes: separate but

often interrelated

Seed germination: Depends on both external (environment) and internal (embryonic)

conditions [seed maturity]

Environmental: water, oxygen, + temperature, light

Seed quiescence: Depends on factors in the seed itself – ‘suspended animation’

Released when proper conditions for germination are present

Seed dormancy: Depends on factors within the seed itself (but may require

environmental cues that promote it)

Released by exposure to proper environmental conditions (the ‘triggers’) which ‘break’ dormancy and allow germination

Germination will not occur unless dormancy is broken

© Project SOUND

Quiescence: a temporary hold on germination

Often due to seed dehydration

Seeds in state of ‘suspended animation’ ; ready to germinate once environmental conditions change for the better The seed reaches soil

The first rain

The temperature warms up

Etc.

The risks associated with quiescence strategy: premature germination if conditions again change for the worse [hot, dry conditions after the first rain]

© Project SOUND

ZZZzzzzzz

http://unrealnature.wordpress.com/2008/10/27/some-assembly-required/

Dormancy: longer term strategy

Is a characteristic of the seed itself (not the environment); some seeds [those from tropical regions; typical garden plant seeds] exhibit no dormancy

Some CA native seeds are dormant when they leave the plant (primary dormancy) – insures dispersion will occur prior to germination

Others only become dormant only when they experience unfavorable conditions (too dry; too hot or cold) – secondary dormancy

Difference between fresh seeds and ‘older’ seeds is usually explained by secondary dormancy

Dormant seeds will not germinate unless dormancy is ‘broken’

© Project SOUND

Germination and dormancy are two

different processes

© Project SOUND

http://www.rtbg.tas.gov.au/index.aspx?base=332

The life cycle of seeds: mediterranean climates

© Project SOUND

http://www.rtbg.tas.gov.au/index.aspx?base=299

Why is seed dormancy important?

Ensures time for seed dispersal

Prevents germination during unsuitable ecological conditions

Enables seeds to survive short periods of favorable conditions; when germination stimulating factors are present, but prevailing conditions are not suitable for subsequent seedling growth and plant development.

Prevents germination of all the seeds at the same time. The staggering of germination safeguards some seeds and seedlings from suffering damage or death from short periods of bad weather, transient herbivores, etc

© Project SOUND

In other words, the dormancy evolved as a mechanism to

postpone germination until a time and place that not only

supports germination, but also maximizes seedling

establishment and growth.

Seed dormancy: many variations

Seed coat-imposed dormancy [AKA Exogenous/External dormancy] - caused by an impermeable seed coat

Embryo-imposed dormancy [AKA Physiological/endogenous/ internal dormancy] – caused by the embryo itself; prevents embryo growth and seed germination until chemical changes occur within the embryo not due to any influence of the seed coat or other surrounding

tissues

most abundant form of seed dormancy in angiosperm

thought to be due to the presence of inhibitors, especially ABA, as well as the absence of growth promoters, such as GA (gibberellic acid).

Combinations – why it’s sometimes hard to determine the factors needed to ‘break dormancy’ in a given species

© Project SOUND

Seed coat-induced dormancy: several

common mechanisms

Seed coat prevents water or oxygen uptake: [waxy coatings; special layers in seed coat that block water]

Hard seed coat prevents embryo from growing/emerging [coat must be softened/broken by exposure to stomach acids; mechanical means]

Seed coat contains growth inhibitors [must be leached away be repeated rinsing; exposure to chemicals that break down the inhibitors]

© Project SOUND

Seed coat-induced dormancy: breeching

the seed coat

Seed coat must be broken down to allow entry – embryos will germinate readily in the presence of water and oxygen once the seed coat and other surrounding tissues are either removed or damaged.

Is usually all or none: once seed coat is breeched there’s no turning back – so timing is critical

Typically found in species from the families Fabaceae, Malvaceae, Chenopodiaceae, and Liliciae

© Project SOUND

http://www.seedsplants.kimeracorporation.co

m/articles/19-come-seminare-.html

Scarification: breaking/fracturing seed

coat to facilitate water/gas uptake

Mechanical : tumbling, abrasion, ‘nicking’, pounding etc.

Chemical : usually involves acid treatment like concentrated H2S04 (sulfuric acid), other acid treatments

Physical : hot water treatment; other heat treatment (burning)

Soaking/leaching : some seeds

© Project SOUND

http://www.organicgardening.com/learn-and-grow/pretreatments-slow-

germinate-seeds

http://mpgranch.com/staff-blogs/tales-of-a-

transplant/scarification-and-stratification.aspx

Treatments to break embryo-induced

dormancy vary by plant

Common requirements/ treatments

Drying [after-ripening]

Low temperatures [stratification]

Alternating soaking/drying

Applied by mother nature – or by the propagator

Clues from the native environment of the plant

© Project SOUND

Hollyleaf redberry grows

in dry places, often with

colder winters – may

require stratification

Chilling (stratification): exposure to cold-

moist conditions

Prevents temperate climate seeds from germinating until the spring

Temperatures: 0-10° C (32-50° F)

Time: usually 1-3 months; seed supplier may specify

Seeds need to be fully hydrated – stratify in moistened vermiculite or moist paper towel/coffee filters in refrigerator

Need access to oxygen (air)

© Project SOUND

Garden collected seed – may

want to wash first in mild (5%)

bleach solution to prevent fungal

contamination

Some environmental conditions that break

embryo-induced dormancy in CA native plants

Drying [after-ripening - grasses]

Low temperatures [stratification]

High temperatures [heat stratification]

Light (or dark) exposure

Fluctuating temperatures (repeated heating and cooling over many months-years),

Fire/smoke chemicals

Freezing/thawing (may require cycles)

Passage through the digestive tracts of animals/birds

Removal/breakdown of fleshy fruit

Acid treatment

© Project SOUND

Important points about CA native seeds

They differ in the amount of stored food Small amounts - must start producing quickly

Large amounts – live off stored ‘food’ for a while

They differ in the composition of their seed coat –some are harder than others

They germinate in response to cues (all seeds) Water – cue + softens coat (all plants)

Oxygen

Light (small seeds)

+Temperature

Some seeds are actually dormant until ‘awakened’ by environmental exposures

© Project SOUND

Implications for gardeners: seeds

Storage: Store seeds cool and dry

In general, smaller seeds have shorter ‘shelf-life’ than larger seeds

Planting: Know if your seeds need pre-

treatment to break dormancy Seed company instructions

On-line

Inference: place of origin; taxonomic

Plant seeds at the correct depth – some need light to break dormancy

© Project SOUND

http://www.sierraclubgreenhome.com/go-green/landscaping-and-outdoors/organic-seeds/

Once seeds have germinated,

be sure to keep them adequately

watered – very vulnerable to

dehydration

Be patient: just because you don’t see

anything, doesn’t mean nothing is

happening

Root development may occur before shoot development – particularly in large seeds [acorn]

Dormancy due to germination inhibitors may take some time

Cycles of hot and cool

Cycles of wet and dry

Many ‘washings’ to leach away or chemically modify the inhibitors

© Project SOUND

http://www.roguehydro.com/germinating-your-seeds/

How do plants grow? By adding modules

All plants are based on same basic pattern: Shoot system

Main stem

Laterals (branches)

Root system Primary root

Lateral roots

© Project SOUND http://leavingbio.net/flowering%20plants.htm

http://en.wikipedia.org/wiki/Plant_stem

Shoot and root elongation and development

is segmental in plants

Phytomere: developmental segment for shoot (shoot module) or root (root module)

Phytomeres develop from unspecialized cells in special areas of the plant – the apical meristems

Plant meristems: the plant’s ‘fountain of youth’

Apical meristems (shoot and root) At the shoot and root tips

Give rise to the shoot or root modules

Result in elongation

Axial meristems Located at/near a node

Give rise to branches

Lateral meristems Located internally in

shoots/branches

Responsible for growth in girth

© Project SOUND http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html

What do the meristems look like?

Central area with lots of simple cells

Surrounded by area of smaller cells (due to cell division)

Cells are more specialized looking (and larger) the further away from the meristem they are

© Project SOUND

http://www.sbs.utexas.edu/mauseth/weblab/webchap6apmer/6.1-1.htm

http://mrzacbio.blogspot.com/

All cells, tissues & organs arise form cells

in the apical meristems

Can traced origins back to the meristems

“Fate maps” can be drawn to trace the evolution of developing tissues

Apical meristem contains

Concentric rings of cells

Outer-most rings (segments) form lowest sets of leaves/stem segments

Pattern of development is somewhat like the water coming out of a fountain

Phyllotaxy – the arrangement of

leaves on the stem

Is genetically determined – that’s why it’s often used in taxonomy & plant keys

Is determined by how much each new segment is offset around the stem

© Project SOUND http://www.ecotree.net/fall_2011.shtml

http://everydayfibonacci.tumblr.com/

http://www.biologie.uni-hamburg.de/b-online/virtualplants/ipi_ic2.html

Leaf arrangement/position (in relation to

others) – phyllotaxy

© Project SOUND

©2009 Robert Steers

© 2002 Kristiaan Stuart

Why do plants grow (at least in part) by

adding new segments?

Because that’s how they evolved

Efficiency: particularly in an ever-changing environment

Redundancy/backup : plants need to be able to regenerate lost parts

As a consequence of a need for rigid structure

© Project SOUND

http://www.calflora.net/bloomingplants/hollyleafredberry.html

Plant cells are a little different from our cells

One of the big differences is that they form cell walls

Primary cell wall Formed first – just inside the

cell (plasma) membrane

Strong but flexible

Allows for growth in certain directions (for example, cells can elongate)

Secondary cell wall Formed inside the primary cell

wall

Very strong; inflexible

No growth after secondary cell wall is formed

© Project SOUND

http://acseenotes.wordpress.com/2011/03/07/cytology/

What the heck! Why would plants do that?

Strong cell walls give plants the structure needed to grow tall

But plants still need to keep growing

Solution: add new segments on top of the old – requires apical meristems © Project SOUND

http://www.doitpoms.ac.uk/tlplib/wood/structure_wood_pt2.php http://montessoriworkjobs.blogspot.com/2011/10/human-skeleton.html

Consequences of sedentary life: scary!

Plants need to keep ‘rejuvenating’ themselves throughout life – roots and shoots

Therefore they continue to grow throughout their lives – sometimes for 1000+ years

In order to grow they need functional meristems [plant stem cells]

But what happens when something happens to an apical meristem (disease; herbivory)?

© Project SOUND

Ancient (senescent) Bristlecone pine

Fortunately, plants have a backup system

In most plants – most of the time – segments are added by the apical meristems

But there are ‘backup meristems’ – the axial meristems

Development of axial meristems is limited to a degree by the functional apical meristem – produces an inhibitory hormone

Once the apical meristem is gone, the axial meristems take over the job of elongation

© Project SOUND http://vannocke.hrt.msu.edu/plb865/31oct/meristems.html

The shapes of plants

http://www.wildmanstevebrill.com/JPEG'S/Plant%20Image

s/Chicory.Rosette.jpg

http://www.unc.edu/~hallman/cookbook/pumpkin-vine.jpg

http://www.co.columbia.wi.us/dept/lwcd/images/tree.gif

http://www.houstonrose.org/ghbush.jpg

Stem elongation and control of the number of main shoots

The length of the internode is one

determinant of plant shape

© Project SOUND

http://www.doyletics.com/digest51.shtml

The main difference between the shape of a cabbage and a Southern honeysuckle vine is the length of the internodes

The length of the internode: genetics and

environment

© Project SOUND

©2009 Robert Steers

Southern honeysuckle - Lonicera subspicata

Turkish rugging - Chorizanthe stacticoides

Take home messages

© Project SOUND

The basic structure (growth pattern/shape; mature size) is genetically determined. Choose plants accordingly

But…plants have enough flexibility programmed in to allow them to modify their shape based on conditions:

Limited water/nutrients – shorter internodes

Limited light – longer internodes as plant ‘reaches for the sun’

But internode length doesn’t explain all of

the shape variability

© Project SOUND

Torrey pine - Pinus torreyana Lemonadeberry – Rhus integrifolia

Apical dominance:

not all or none

Several plant hormones involved – degree of apical dominance depends on balance of these

Degree of apical dominance is genetically determined – that’s why a pine tree has a strong central leader and a shrub has many equal ‘stems’

You can (sometimes) make a strongly dominant form more shrub-like; it’s more difficult to go the other way around

© Project SOUND

http://plantphys.info/apical/apical.html

http://www.tutorvista.com/content/biology/biology-iv/plant-growth-movements/growth-

regulators.php

Tip-pruning (‘pinching’) removes apical

dominance creating a ‘bushier’ plant

Just remove the tip – don’t need to take much

Must be done during periods of active growth

Must do repeatedly for best effects – new side branches will also exhibit apical dominance

© Project SOUND

http://www.studyblue.com/notes/note/n/botany-exam-3/deck/1607515

How far back can I safely tip prune/ prune to

head back?

Lateral buds have an age – oldest at the base of a stem/trunk and youngest at the top

How long do lateral buds retain the ability to grow? Alas, no one answer.

But there are some rules of thumb: Generally - but not always – lateral

buds in older woody parts of stems have decreased/no growth potential

Generally – but not always – buds in semi-soft or soft wood (younger parts of stem) will grow

© Project SOUND

Take home messages: pruning/shaping

When shaping woody plants, start when plants are young

Know taxa that require careful pruning: Ceanothus spp

Arctostaphylos spp

Salvia spp

Pinus spp

Prune ‘difficult’ species either:

During growth period (when wood is still semi-soft) for tip-pruning

When you can clearly apply the ‘leave 3-4 leafing buds’ rule

© Project SOUND

What ‘materials’ do plants need from their

environment?

Sunlight Photons of light (energy for

photosynthesis)

Air Oxygen (to break down stored

food)

Carbon dioxide (CO2) (for photosynthesis)

Soil/medium Water

Nutrients (minerals/ fertilizer)

© Project SOUND

http://www.nelsonthornes.com/secondary/science/scinet/scinet/plants/nutri/c

ontent.htm

How do these move around the plant?

Roots (root hairs) are where water and

minerals enter the plant

Good soils contain what plants need:

Water

Mineral nutrients (dissolved in the soil water)

Oxygen (needed by the roots so that they can obtain energy & perform their functions)

© Project SOUND

http://www.aaronthomaslandscapes.com/blog.html

The importance of soil water/oxygen balance

Too much water Root oxygen depleted – decreased uptake of water, minerals

Too little water Roots cannot uptake water or dissolved minerals

© Project SOUND

http://www.stevenswater.com/articles/irrigationscheduling.aspx

That’s why the symptoms or over- and under-watering are the same

Root characteristics: especially important

with CA native plants

Coastal sage scrub shrubs Primarily fibrous roots

Primarily shallow roots (< 3 ft)

Root:shoot ratio increases with water & nutrient stress

Chaparral shrubs Combination of deep and

shallower roots

Root growth in spring/ summer

Root:shoot ratio increases with water & nutrient stress

© Project SOUND

http://www.rmrs.nau.edu/watersheds/highlands/vegetation/chaparral/chpla

ntwater.html

Individual species have

characteristic root growth patterns

Root characteristics of some common CA

native shrubs

© Project SOUND

Use root characteristics to choose the

proper plant – and treat it well!

Taproot Likely very drought-tolerant

Plant is out young – don’t move

Not for containers

Fibrous roots Look for depth characteristics

Shallow

may need occasional or regular water

Take care when digging

Good for containers

Good choice for slopes, banks

Lignotuber Fire-adapted; may require occasional

rejuvenation © Project SOUND

http://nativeplants.msu.edu/getting_started/how_to_plant/establishment_

of_rooted_plant_material

We’ll discuss roots more next month

© Project SOUND

Development of the

vascular system

New segments of vascular system are added by apical meristems

New layers of vascular tissue in older segments are added by lateral meristems (called vascular cambium)

http://cnx.org/content/m43140/latest/

http://cnx.org/content/m47400/latest/?collection=col11569/latest

© Project SOUND http://www2.puc.edu/Faculty/Gilbert_Muth/phot0010.jpg

http://sci.waikato.ac.nz/farm/content/plantstructure.html

Benefits Two systems in close

physical proximity – key to water/nutrient movement

Easy access for loading & unloading throughout the plant

New tissue can be added – even in woody parts

Somewhat protected (fiber cap; bark)

Drawbacks Vulnerable location

Location of

vascular tissues

Take-home messages: plant vascular system

© Project SOUND

Soil water status is important not only for plant water needs, but also for mineral nutrition – more next month

Plant vascular tissues move all sorts of vital things around the plant body – an intact system is a must

Vascular tissues are vulnerable: Girdling

‘sucking’ insects [aphids]

Transport of toxins

http://caseytrees.org/blog/summer-tree-care-making-gardening-and-lawn-

care-safe-for-trees/

https://extension.umd.edu/learn/homeowner-landscape-series-common-

cultural-and-environmental-problems-landscapes-hg201 http://cnx.org/content/m47400/latest/?collection=col11569/latest

We hope you look at plants differently

© Project SOUND

Read a botany book

Use on-line resources – and refer others to them

Come back next month when we consider the effects of climate change

© Project SOUND