Plant taxonomy 1.

1

Basics of taxonomy

The unit in taxonomy = taxon

The basic unit of biological classification:

the species

„An individual belonging to a group of

organisms having common

characteristics and (usually) are capable

of mating with one another to produce

fertile offspring.”

New and new terms to determine species

(e.g. ecological species, phylogeneticspecies) � a group whose members

are descended from a commonancestor

Morphology vs. relations based on

molecular markers 2

Intrespecific taxonsSubspecies (subspecies): specific geographical distribution or

ecologycal attributes

Variety (varietas): no specific geographical distribution, but

specific heritable attributes

Form (forma): noticable morphological deviation with but

inheritance may be doubtful

Nomenclature of cultivated plants:

Cultivar (cultivar)

Cultivated botanical variety (provarietas): a

group with similar morphology

Cultivated race (convarietas) consists of

similar groups of varieties

3

Higher taxonomic ranks

Species

Genus (genus)

Family (familia): -ceae

Order (ordo): -ales

Class (classis): -opsida

Phylum (division) (phylum): -phyta

Euphorbia cyparissias – cypress

spurge

Euphorbia – spurge

Euphorbiaceae – spurge f.

Malphigiales –

Dicotyledonopsida – dicots

Magnoliophyta – angiosperms

4

Groups of the modern taxonomyThe basic unit is the clade: consists of common ancestors and

all the lineal descendants

Revision of former

groups: e.g.

monocots and

dicots (no common

ancestor)

5

Divisions of algae

Phyla of prokaryotes and

eukaryotes with ~ 40-50 000 taxa

Uni- or multicellular forms withouttissues and organs that produceoxygen

Size can range from µm up to 50-

100 meter sized individulas

Species colonize dried and moist

habitats including extreme

environmental conditions (e.g.

hypersaline lakes, polar sites,

geothermal wells)

6

The importance of algae

Supply 60% of the world’s

oxygen source

Importance in freshwaterfoodwebs (phytoplankton) �

fishery and fish flour production

are based on the organic matter

produced by algae

Fixation of atmosphericnitrogen

Dietatic food supply for humans

Forage supply for livestock(protein supply, decreasingrumen acidosis)

Indicators of freshwater quality7

Algae poisoningWaterbloom of drinking water

Mainy caused by cyanobacteria

Neurotoxic alkaloids (e.g. Anabeana spp.),

hepatotoxic compounds (e.g. Nostoc spp.)

Poisonings are rare, occurs mainly in summer if

there is a heavy waterbloom

Ruminants, birds and dogs are susceptible

Nostoc spp.

8

Lichens

Formerly an individual phylum,

currently lichens are a group of fungi

For fungi � see lecture 13., 14.

A colonial symbiotic organism

consists of mycobiont and

photobiont

~ 13 000 species worldwide

About 700 different secondarymetabolites, and ~ 650 occures

only in lichens (lichen acids or lichen

substances)

9

The importance of lichens

Species are used as an expectorant(Lobaria pulmonaria, Cetraria islandica)

Some species (Usnea spp. – old man’sbeard) have antibiotic effects �

medicinal, veterinarian application

Natural forage (reindeer lichen)

Widely used in cosmetics and paintsLobaria pulmonaria –

lung lichen

Cetraria islandica –

iceland moss

Usnea barbata –

beard lichenCladonia rangiferina –

reindeer lichen10

Divisions of mosses

Formerly it was one division,

which currently divided into three

different ones

A transitional group between

vascular and non-vascular

species

The two biggest divisions are

mosses and liverworts

No specific veterinarianimportance

They have a major ecological

role

Marchantia polymorpha –

common liverwort

Hypnum cupressiforme –

cypress-leaved plaitmoss11

Divisions of fernsThe first vascular plants with vascular tissues

1. Division of clubmosses

2. Division of true frens and horsetails

Presence of rhizome for both groups

Horsetails: SiO2 crystals in epidermalcells, scale leaves are fused into a sheath,

sporangia (an enclosure with spores) at the

stem apex

Lycopodium clavatum –

stag’s horn clubmoss

12

True ferns: simple or multiply divided

leaves, sporangia arranged on the

underleaf, dichotomous venetion

Typical poisonous

compounds:

• thiaminase

• ptaquilozide

13

Divisions of gymnospermsThe first flowering plants

Flowers can be solitary but

generally form cones

Carpels not fuse to each other �

unenclosed seeds � gymnos (in

Greek): naked, sperma (in

Greek): seeds

Sperm no longer needs water to

fertilize the egg

Cones can be fleshy � cedars,

junipers

Several poisonous ormedicinal plants

Rarely grazed or nibbled by

animals 14

The major gymnosperm groups

Cycads: palm-like appearence, with

stout and woody stem, evergreen

pinnate leaves

Non-proteinogenic amino acids(neurotoxins) and carcinogenicglycosides

Gingko tree: only one extant

species (Gingko biloba),

dichotomous leaf venetaion,

medicinal effect (CNS)

Yew species: needle-like leaves,

absence of resin ducts, generally

aril covers the seed

Diterpenoid compounds Ginkgo biloba – ginkgo tree

Cycas revoluta – sago palm

15

Cypress species: scale or needle-like

leaves, small cones

High proportion of volatile oil � toxic effects

may possible (e.g. thujone)

Juniperus communis

– common juniper

Thuja occidentalis –

northern white-cedar

Pine species: needle-like leaves, high

proportion of resin, generally large cones

Good quality wood

Poisonous compounds generally not present

Pinus sylvestris –

Scots pine

Larix decidua –

larch16

Angiosperms

Major groups of „monocots”

17

General morphologyProduction of fruits

Fibrious root system

Non-branched stem

Modified underground

stem occurs generally

Herbaceous stem

without secondary

growth

Leaves have generally

no petiole

Generally six tepals

18

Araceae – arum familySpecies naturally occurs mainly under

tropical climate, only a few taxa

distributed in Europe

Species with creeping stem or

epiphytes (grow on trees)

Tubers and rhizomes and aerial roots

generally occures

Leaves are shiny and undivided

19

Monosexual and

monoecious flowers

Flowers are coverd with a

large bract leaf (insect

trap)

The fruit is a berry

20

Typical compounds: cyanogenicglycosides, oxalate crystals, flavonoids

Importance: most common plant familyof many household plants

In natural habitats of Europe only a few

poisonous species occurs

Cultivated species (e.g. taro - Colocasiaesculenta � raw tubers are toxic)

Arum maculatum –

lords-and-ladies

Colocasia esculenta

– taro

Spathiphyllum

wallisii – peace lily21

Liliales – order of lilies

Formerly many species were

classified in to the Liliaceaefamily � currently they belongs

to smaller families

Most of the species arecultivated for ornamentalpurposes

Underground stems

(Narrow), elliptic leaves

2x3 fused or free tepals with

nectar glands

Large, conspicuous, colorful

flowers

Generally the fruit is a capsule22

Major compounds:

• Colchicine (meadow saffron)

• Sesquiterpene lactons (tulip)

• Steroidal alkaloids (Veratrum spp.)

• Steroidal saponins

� most of the species more or less toxic

Tulipa gesneriana –

tulipLilium spp. – true lily

Gloriosa superba –

flame lily

23

Juncaceae – rush family

Species distributed

worldwide

A grass-like morphology

Cylindrical stem and leafwith aerenchyma tissue

Generally glabrous species

without hairs

Tuft-like appearence

24

Small, brown, scale-like tepals

There’s no spikelet!

Tepals enclose the capsule with

dust-like seeds

Inflorescence bracts can be

present

Toxic compounds are rare

25

Importance: species can be present in hay samples

Generally low digestibility and nutritive value

Species are used for animal

bedding

Planted in garden ponds

Uncertain identification belowthe genus level

Juncus effusus –

common rush

Juncus compressus – roundfruit rush

26

Cyperaceae – sedge family

Species distributed worldwide

A grass-like morphology

Triangular, sharp and coarsestem � SiO2 crystals

Leaves covers with cuticule and

have a W-shape

27

Tepals are reduced or absent � „spikelet”

(different from grasses)

Monosexual flowers, staminate and

pistillate flowers can be arranged in the

same or different spikelet

Flowers covered with a glume

Female flowers surrounded with a bottle-shaped bract � utricle

28

Importance: species can be presentin hay samples

Generally low digestibility and nutritive value

Consumption of the plants can damage

the mouth

Planted in garden ponds

Uncertain identification below thegenus level

Carex stenophylla – narrow-

leaved sedge

Carex distans – distant

sedge

29

Poaceae – grass family

For detailed morphology � see

seminar 1.

Spikelets with 1 or more florets

Toxins rarely occurs exept

cyanogenic glycosides

Endophytic fungi can produce

toxins (e.g. lolitrem B)

Fructan accumulation of somespecies � laminitis

30

Grasses, sedges, rushes

31

Practical importanceBotanical hay analysis

The presence of „sour grasses” (sedges, rushes) can

decrease the quality of the hay

Low nutritive value, higher antinutritional effect

32

Other monocot families in the

veterinarian practiseIridaceae – iris family

Flavon glycosides, mild

toxic effects

Amaryllidaceae – amaryllis

family

Alkaloids, non-proteinogenic

amino acids, fructans

Galanthus nivalis –

snowdropIris germanica – german

iris33