Plant Life Cycles

What makes a plant a plant?

And not a . . . ?

PhotosynthesisPhotosynthesisSimply put. . . Sequence of reactions performed in green plantsLight energy converted into chemical energy

In English. . . . Carbon dioxide + water + light yields Sugar and oxygen

Plant Life Cycles

AnnualsBiennialsPerennialsHerbaceous perennialsWoody perennials

Annuals

All in one growing seasonCool season or warm season

Germination & vegetative

growth

Reproduction – flowering, seed production &

seed dissemination

Death

Annuals (cont.)

Fast growingDifficult to compete in natural settingsSeeds must store enough food for seedlings to develop quicklyMain reason we don’t see annuals in many natural settings

Annuals (cont.)Annuals can be found in the desertsFew herbaceous perennials for competitionSeeds can last yearsWith available water – rapid growth

Cool Season Annuals

Seeds germinate with fall rainsWarm days and soilsCool nights and shorter daysRapid seedling development Fast growthFlowering late winter to early springSeeds mature and disseminated Quick process where water is scarce

Cool Season AnnualsSome of the more common cool season annuals in our area Snapdragon (Antirrhinum)Stock (Matthiola)Pansy, Violets (Viola)Primrose (Primula)Forget-Me-Not (Myosotis)Sweet peas (Lathyrus)See the Sunset Western Garden Book pg. 70 & 71 in this previous edition

Cool Season Annuals

Pansy

Stock

Snapdragon

Forget-Me-Not

Sweet Peas

Warm Season Annuals

Warm season annualsSeeds germinate with late winter and spring rainsCool days and soilsRapid seedling development Fast growthFlowering late summer to early fallSeeds mature then disseminated

Warm Season Annuals

Biennials

Requires two growing season

Reproduction – flowering, seed production &

seed dissemination

Death

Season 1 Season 2

Germination & vegetative

growth

Biennials

Often grown as annualsRarely woody Occasional secondary woody-like growth

Biennials

Some of the more common biennials grown in our area:Foxglove (Digitalis) Queen Anne’s Lace (Daucus)Carrots (Daucus)Sweet William (Dianthus)

Biennials

Foxglove

Sweet William

Carrots

Queen Anne’s Lace

Perennials

PerennialsDivided into 3 groups — herbaceous and woodyCan be long livedAnnual vegetative and reproductive cyclesCycles are seasonal

Daylily

Herbaceous Perennials

Grow vegetativelyIn warm or wet seasonsDormant in cold or droughtNon-woodyPeriodic burn cyclesSurvives using underground storage organs – roots, bulbs, tubers, rhizomes, corms and stolons

Geophytes

Modified stemsPlants with buds undergroundAssociated with underground storage organsRhizomes, tubers, corms and bulbs

“Bulbs”A “catch-all” term for underground storage organsProvides a reserve of nutrientsIncludes true bulbs, tubers, tuberous roots, corms, and pseudo-bulbsMostly deciduousStored reserves allow dormant survival Provides propagative materials

BulbsTrue bulbsMonocots – many lilies and amaryllis Grows at or just below the soil surfaceHighly modified stem or basal plateAdventitious roots

Anatomy of a bulb

Bulb Anatomy

or bulblets

Bulbs

Flowers often emerge firstReproduction can carry on immediately after dormancyCompetition from shade is reduced

Common Bulbs

Garlic

Corms

Bulb-like monocotsUnderground storage at or below soil lineModified stem with basal plateGrowth points on top of cormNew cormels formed for each seasonCormels form on top of corm

Corm Anatomy

Corms

RhizomesModified stemsAt or below soil lineThick, fleshy and fibrousAdventitious roots along bottom of rhizomeBuds at ends of rhizomesDivisible for propagation

Associated with monocots

Anatomy of a rhizome

Common Rhizomes

Common Rhizomes

Ginger root

TubersAt or below soil lineSolid and fleshyAssociated with dicotsRoots can emerge from anywhere on the surfaceBuds or “eyes” found over the surfaceEyes used for propagation

Anatomy of a tuber

Common Tubers

Tuberous Roots

Modified rootsLarge, finger-likeBuds form at proximal endRoots form at distal endCan be used for propagation Anatomy of

tuberous roots

Common Tuberous Roots

Dahlias

Ranunculus

Daylily

Stolons

Modified stemsGrows along soil surfaceStolons develop roots and shoots at nodes

Anatomy of a stolon

Common Stolons

St. Augustine Grass

Strawberry

Spider Plant

Plant Life Cycles (cont.)

Woody PerennialsLives more than two yearsCan have extremely long life spansAnnual vegetative – reproductive cycleCycles are seasonal

Largest

Oldest

Woody Perennials