Hort234 Exam 1

characterization

description of plants, characteristics

identification

inventory of plants, keys or floras

nomenclature

naming of plants, scientific names

classification

plant relationships, orderly system expressed on evolutionary relationship

plant taxonomy

• characterization

• identification

• nomenclature

• classification

common plant names

• real words

• not part of scientific name

• not governed by ICBN

• selected by major characteristics, native range, use, or significant person/discoverer

• not capitalized unless proper noun, never underlined or italicized

common names and why to learn scientific names

1. not universal - same scientific name known globally

2. some plants can have several common names; two plants can have the same common name

3. no rules for common names - confusion; no ICBN

4. plants can have different common names in different languages/regions

5. many common names are confusing; no info on ID featues; Latin names often give descriptions

6. common names can apply to several plants

7. common names have no common affinities (poison oak vs Quercus)

classification and scientific names

• each species has one Latin scientific name

• common names, patents, and trademarks not part of scientific names

Carl Linnaeus

• father of taxonomy and binomial system of nomenclature

• wrote Species Plantarum in 1753

• grouped plants according to number of flower parts

• book is starting point of Principle of Priority

• earliest published Latin scientific name starting in 1753 is correct

modern nomenclature

• phylogenetic classifications (genealogy/common ancestry + evolution)

• goes beyond # of flower parts (Linnaeus system)

• evidence from morphology, biochem, and gene sequence (DNA) data

• called Angiosperm Phylogeny Group Classification

Angiosperm Phylogeny Group Classification

• all orgs genetically related; Tree of Life

• history of organismal lineages as they change through time

• different species arise from previous forms

• connected by passage of genes along the branches of the tree

reasons for scientific name changes

• misidentification of plant

• change in taxonomic judgment (plant now belongs in another family, genus, or species) based on new phylogenetic system

• ICBN rules not originally applied correctly to plant name (Principle of Priority)

nomenclature rules

• plant scientific names goverened by Internation Code of Botanical Nomenclature

• cultivars covered under International Code of Nomenclature for Cultivated Plants (ICNCP)

plant name authority

author who originally names and published a plant’s scientific name in accordance with ICBN rules

• placed after scientific name in scientific literature only

family name

assemblage of genera, or single genus, that resemble each other in characteristics, especially reproductive structures (flowers, fruit, seed)

• usually named after a genus and are capitalized but not underlined or italicized; -aceae

reasons to learn family names

• ease of relating similar plants in same family that look different vegetatively, but reproductive structures are similar

• certain insects and diseases known to attack certain families

• certain plant families require specific cultural requirements

• aids breeders and propagators as a genus may be bred with another genus within the same family, or grafted onto each other

genus

group of closesly related plants that have similar morphological features than they do with other genera within the same family

• first word in scientific family

• one word noun

• always capitalized and underlined or italicized

intergeneric hybrid

hybrids between two different genera in the same family

• part of the female parent genus name is listed first, second is part of male parent name

• multiplication sign in front of generic name; not underlined or italicized

• new hybrid genus name is capitalized and underlined or italicized

• rare in woody plants

• can occur in wild (rare); usually human engineered

species

group of plants whose variation comes from a common genetic pool (freely interbreeding)

• reproductively isolated from other plants

• have distinct morphological features that’re different from other members within the genus

• all individuals are not identical

• Genus + specific epithet (adjective that describes genus; never capitalized)

• singular: sp.; plural: spp.

specific epithet

adjective derived from morphological features, origin of plant, or in honor of someone who found the plant in the wild

interspecific hybrid

hybrids between two or more different species within the same genus

• small multiplication sign after genus, before specific epithet; not underlined or italicized

• common in woody plants

• can occur in wild; can be human engineered; very common

• specific epithet is not part of either parents’ genus or specific epithet names

• when parentage of interspecific hybrid is unknown/there are several parents, hybrid listed by genus and cultivar name without a specific epithet; ex. Tilia ‘Redmond’; no multiplication sign

Keys

• help figure out what plant you have

• Series of steps based on id features

• Make choices at each step of outline

• General to specific features

• Some easy, some technical

• Must know definitions of terms

Leaves

• below lateral bud

• Apical meristem in terminal and axillary buds

• Deciduous lose leaves in autumn

• evergreen broad or needle-leaved, shed old, inner leaves every year or every couple of years

morphology variability

leaf size, leaf shape, and plant height are variable whereas flower and fruit type are not

leaf and bud arrangement

branching and buds have the same arrangement as leaves for all plants

alternate arrangement

most common; 1 leaf/bud per node in a spiral arrangement down the stem

opposite arrangement

two leaves/buds per node at right angles to each other

decussate arrangement

leaves are opposite and arranged on the stem so that they alternate at right angles to the pair of leaves above and below them; evolved to not shade pair of leaves below

subopposite arrangement

leaves and buds are not quite opposite, but not enough to be alternate; rare; can have some opposite and subopposite leaves on the same stem

whorled arrangement

three or more leaves/buds per node on a twig; rare

basal arrangement

all stems and leaves arise from base of plant

simple leaf type

only one leaf at one bud; continuous leaf blase, bud located in axil of a single leaf petiole, no leaflets; 1 blade, 1 petiole; rarely sessile

compound leaf type

composed of many leaflets all together comprising one leaf, has one bud located at axil of leaf to stem

pinnately compound leaf type

four or more leaflets attached to a central rachis but not at the same point; each leaflet has its own petiolule or is sessile; consists of:

• petiole: main axis that connects the rachis and leaflets to the stem

• rachis: main axis that bears the leaflets, starts where first leaflet occurs

• leaflet: division of a compound leaf

• petiolule: stalk of an individual leaflet in a compound leaf; absent if leaves are sessile

odd or even, with 1 or two terminal leaflets

bipinnately compound leaf type

has several pinnately compound leaves attached to a rachis; twice divided, rarely seen

• also has rachilla: secondary main axis that bears the leaflets; a small rachis present only in these leaves

palmately compound leaf type

five or more leaflets joined at the same point on the petiole; leaflets may be sessile or have petiolules; rachis and rachilla disappear

trifoliate compound leaf type

only three leaflets joined at the same point; leaflets may all be sessile or all have petioles or only one; rachis and rachilla disappear

dimorphic leaf variation

plant has more than one kind of leaf type or lobing on a plant; leaf size is normal; not due to environmental conditions or age of plant

leaf shapes where widest part of leaf is the middle

• needle

• linear

• elliptical

• oval

• oblong

• oribicular

• rhombic

• reniform

leaf shapes where widest point is below the middle

• lanceolate

• ovate

• deltate

• cordate

leaf shaped where widest point is above the middle

• oblanceolate

• obovate

• spatulate

heterophylly

leaf characteristic where leaf type is the same, but leaf shape and size can vary based on environmental conditions, such as light levels in the tree canopy or the age of the plant

• sun leaves often smaller, deeper lobed, and thicker

• shade leaves can be larger, less lobed, and often thinner

veins

form first; form distinct pattern; contain xylem and phloem

palmate veins

leaf has strong main, central axis through middle of leaf with larger side veins of equal size

pinnate veins

has one main, central vein through middle of leaf with smaller side veins that do not arise from a common point

dichotomous veins

freely arranged veins from the base of the leaf towards the apex; veins branch or fork into two nearly equal divisions near apex; rare

sickle-shaped veins

veins are arranged along main midrib, but never quite reach the leaf margins’ curved into an arch

impressed veins

leaf veins are situated below the leaf surface and press slightly inward

parallel veins

veins run parallel to each other along the long axis of the leaf

bract

modified, reduced leaf occurring at the base of a single flower, inflorescence, or fruit structure; often different in size, shape, or color than the leaves

stipules

pair of leaf-like appendages found at the base of the petiole or fused to petiole in some leaves; or on a twig at the node below the petiole; often falls off in summer and leaves a scar; some persist

stem primary growth

occurs at apical meristem (inside terminal and lateral buds)

apical meristem

undifferentiated, actively dividing cells at growing tip of terminal and lateral stems inside the buds; responsible for increase in height and spread of plant; growth goes out and upwards

stem secondary growth

occurs at the vascular cambium, located under bark

vascular cambium

produces new conducting xylem to inside of cambium and new phloem to the outside of cambium each year; composed of actively dividing cells; responsible for increase in width or girth of stems/trunk of a plant

parts of a twig

• bud: undeveloped leaf, shoot, or flower

• terminal bud: dormant bud containing next year’s growth

• lateral bud: dormant bud located next to or below terminal bud at a node

• flower buds: can be terminal/lateral; often larger than vegetative buds

• leaf scar: mark on stem where leaf was attached; below lateral bud

• lenticels: small, corky opnenings in bark that allow for gas exchange

• node: right above and below a bud and leaf/leaf scar or petiole

• internode: doesn’t include buds, leaf scars, or leaves

tendrils

modified stems, string-like outgrowths that curl and grasp to support to allow a vine to climb; some have adhesive discs at the end and act like a suction cup for anchoring the vine to a wall

rhizomes

horizontal, underground stems; has buds, nodes, internodes

suckers

shoots originating from below ground, often from rhizomes

stolons

horizontal, above-ground stems; has buds, nodes, and internodes

rootlets

small root; holdfasts that form along a stem; aka adventitious roots

receptacle

expanded, swollen tip of a peduncle or pedical; located at the base of a flower where calyx and corolla attach

pistil

all female flower parts (gynoecium)

• stigma: pollen receptor surface, top of pistil(s)

• style: tube from stigma leading to ovary

• ovary: which matures into the fruit

• ovules: inside the ovary, mature into seeds

stamen

all male reproductive flower parts (androecium)

• anther: pollen producing structure

• filament: stalk holding the anthers

complete flower

flower contains all four parts: petals, sepals, stamens, and pistils

incomplete: missing 1 or more parts

perfect fllower

individual flowers contains both functional stamens and pistils, bisexual flowers

imperfect: either pistils or stamens but not both; unisexual

monoecious

a plant that produces separate male and female flowers on one plant

dioecious

a plant produces only make flowers or only female floers, but not both on the same plant

simple or solitary flower

singular flower, not part of an inflorescence; unbranched; peduncle is directly attached to the receptacle and stem

inflorescence

collection of individual flowers all arranged on a branched peduncle; a compound flower cluster with lots of little flowers all connected together

peduncle

stalk of a solitary flower or fruit or the main stalk of an inflorescence

pedicel

the individual stalk of a flower or fruit that occurs only in an inflorescence or fruit cluster

floret

an individual flower within an inflorescence

indeterminate inflorescence

continues to elongate as the flowers open; top or center flowers open last and the bottom or farthest out flowers open first

spike, catkin, spadix, spikelet, raceme, panicle, corymb, umbel

determinate inflorescence

does not continue to elongate as the flower opens; top or center flowers open first and the bottom or farthest out flowers open last

cyme, head

spike

individual flowers are sessile on the elongated peduncle that is unbranched; often wind pollinated

spikelet

individual flowers are sessile, no pedicels, borne on an elongated central axis that is unbranched; each spikelet consists of one or more florets surrounded by two bracts at the base, one external and one internal; can be arranged on a panicle or spike; often wind pollinated

spadix

showy part of flower is the bract that surrounds the spike-like structure called the spadix that contains the fertile flowers; individual flowers are sessile

catkin

type of dense spike, incomplete flower that bears either female or male flowers; often pendulous with no petals

raceme

individual flowers are borne on an elongated, unbranched axis with stalked flowers on their own pedicel

panicle

individual flowers are borne on a branched, central axis; many stems are located within the inflorescence; compound raceme

corymb

flat-topped or rounded with lower pedicels longer than the upper pedicels; individual flowers are attached at different points along the peduncle

umbel

flat-topped or rounded with pedicels of individual flowers radiating from the same point at the top of the peduncle

cyme

determinate; flowers are borne in broad, flat-topped or rounded structure with the middle or terminal flowers opening first

head

determinate; flowers are made up of ray and disk flowers arranged on a flattened receptacle

fleshy fruit

fruit wall becomes soft and fleshy as it matures, common

drupe, berry, pome, hesperidium, pepo

dry fruit

fruit coat and walls become dry at maturity, not fleshy, common, can be dehiscent or indehiscent

dehischent: follicles, legumes, capsules, pyxis, silique, silicle

indehiscent: achene, nut, nutlet, samara, schizocarp, caryopsis, utricle

drupe

fleshy fruit, outer wall (exocarp) is relatively thin-skinned and middle walls (mesocarp) of the fruit are fleshy or fibrous with the inner wall (endocarp) hard and stone-like with a pit containing the seed on the inside

drupelet

a small drupe, individual segments clustered together to form a raspberry or blackberry aggregate fruit

berry

fleshy fruit developed from a single pistil, soft throughout entire fruit; no pit or central core, often with many seeds; seeds are imbedded in material toward the central part of the fleshy fruit; inner wall becomes juicy, often sweet

pome

fleshy fruit with 5 star-shaped carpels that commonly fuse together in one mass into a papery, central core (ovary); rest of fruit is surrounded by a flehsy, swollen, juicy receptable

derived from an inferior, compound ovary consisting of a modified floral tube surrounding a core

rose family only

follicle

dry, dehiscent fruit with a single carpel that cracks open along one suture line only; has many small seeds

legume

dry, dehiscent fruit with a single carpel that cracks open along two suture lines; a pod with several seeds

Fabaceae only; all members

loment: type of legume that is constricted between each seed

capsule

dry, dehiscent fruit from two or more united carpels that crack open on two or more suture lines; very common dry fruit

pyxis

dry, dehiscent fruit, similar to a capsule, but top part of fruit only falls off, like a cap releasing the seeds

silique

dry, dehiscent fruit with pericarp separating as two halves, leaving persistent, central septum with seed/seeds attached

silicle

a short silique

achene

small, dry, hard, indehiscent fruit with a single chamber or cavity of an ovary containing a single seed attached to fruit wall at one point; all ovary walls are hard stone cells

nut

dry, hard, indehiscent fruit similar to an achene, but the wall is greatly thickened and hardened; one seeded, may have a cap or bracts or is inside a dehiscent husk

nutlet

dry, indehiscent fruit with small nuts with a bract attacged; can be winged and attached in a structure containing numerous nutlets