BIO421 FINALS

Phylogeny - hereditary relationships of any group of organisms

• Evolutionary history of the group

Goals of 19th century Taxonomy:

• Develop a natural system of classification where closely related organisms are grouped. 

• Plant names to be assigned based on phylogenetic relationships. 

Goals of modern plant systematics:

• To understand each of these evolutionary lines

• To have a nomenclature (system of names) that reflects their relationships accurately

Ancient Greece - origin of modern classifications 

Materia Medica - most important book on plant classification from the ancient world

Carolus Linnaeus - established the current system of nomenclature of scientific names 

• [Genus name + species epithet] - the basis of every species’ nomenclature

A set of individuals closely related by descent from a common ancestor

• The most fundamental level of classification

• Members of a species can interbreed successfully, but cannot interbreed with individuals of any other species

• Some species may be capable of interbreeding with closely related species and producing a viable hybrid

• One of the oldest concept of species: Group of organisms capable of producing offspring (BSC or Biological Species Concept: Limited)

Genera - group of closely related species (s. genus)

Family - composed of one, several, pr many genera. 

The levels above family are order, class, division, and kingdom.

• Except for kingdom, genus, and species, the names must have a certain ending to indicate the classification level.

Monophyletic Groupings

• All of the species included in the genus are related to each other by a common ancestor.

• All descendants of that common ancestor are in the same genus.

Polyphyletic Groupings

• Members have evolved from different ancestors.

• May resemble each other only as a result or convergent evolution.

Paraphyletic Groupings

Based on known (inferred) evolutionary history or pattern of descent.

Only considers monophyletic groups

Advantages:

• Classification reflects pattern of evolution

• Classification not ambiguous.

Taxa E and F are both the youngest, neither of them can be the youngest on their own.

• They are sister taxa.

Taxon A is the oldest and the following taxa branch from it (descendants)

Taxon D is the closest to Taxa E and F.

Plants can resemble each other for two reasons:

• They have descended from a common ancestor.

  • Similar features are synapomorphies (homologous features)

• They have undergone convergent evolution.

  • Features like this are homoplasies (analogous features)

• If they do not resemble each other, they are autapomorphies

Determining whether a similarity is due to homology (common ancestry) or analogy (convergent evolution) can be difficult.

• In cladistics, homology is favored and analogy is avoided.

Studying lack of similarity can also be difficult as a small genetic change results in dramatic phenotypic changes in some cases.

DNA is unique in every individual of every species

Differences in phenotype (physical observable characteristics) is also evident in the differences in genotype (genetic data).

Genetic differences can also be detected even if phenotypic characters appear the same.

DNA sequencing permits a new type of study, the evolution of DNA itself.

The original dicot was split to Basal Angiosperms and Eudicots as it was originally paraphyletic.

Genealogy

• Maps the genetic convergence of characters from many ancestors into one descendant over a few generations

Phylogeny

• Maps the evolutionary divergence of characters and progeny over thousands or millions of generations. (e.g. humans, and other mammals)

Diagram that shows evolutionary patterns by means of a series of branches.

Monophyletic Group - includes the most recent common ancestor of the group and all of its descendants

Paraphyletic Group

Polyphyletic Group - does not include the most recent common ancestor of all the members.

Several key characters, often very easy to observe, are chosen as the basis of artificial classification (e.g. roadside floras, common field guides)

These systems are artificial because the plants often do not share a close common ancestor.

Artificial System of Classification

• Use of key characteristics (e.g. color, habit, habitat) without basis on common ancestor

• E.g. group fruits based on types of pericarp, group flowers based on color, group plants based on habitat

A third type of classification, used for fossil organisms, combines features of both artificial and natural systems.

Typically, we do not know much about the fossil. 

• Superficially similar specimens are grouped together for convenience.

All fossils with the same basic form or structure are classified together in groupings called form genera.

Continuous exploration leads to discoveries of new species.

For new plant species, the International Code of Botanical Nomenclature provides the necessary steps for naming.

Type Species - the single preserved plant that carries the characteristics of the name.

All organisms are grouped into three domains: Bacteria (with cyanobacteria), Archaea, and Eukarya

• Eukarya: Animals, Fungi, Plants, Protists

Called “amphibians of the plant kingdom” because they can live in soil but depend on water for sexual reproduction.

Economical Importance: Source of fuel, horticulture, preservative agent, household uses, house construction, pharmaceutical industry, moss industry.

Bryophytes are next to green algae in the phylogeny of kingdom plantae

They are the first land plants.

Under Chlorobionta (Green Plants), and Embryophyta (Land Plants)

Embryophytes WITHOUT vascular tissues.

Embryophytes with multicellular sporangia and gametangia.

With leafy stems (mosses and liverworts) that resemble small flowering plants

• Thallus is present in these

Almost exclusively terrestrial and covered with cuticles,. Stomata is also present.

Has an alternation of generations

• Haplodiplontic Life Cycle: Sporophyte and gametophyte generations (Chromosome #: 2N and N)

• Dominant Phase (visible to naked eye): Gametophyte 

  • Sporophyte is dependent on the gametophyte

Plants are traditionally divided into 3 groups:

• Nonvascular plants - without vascular tissues nor seeds

• Vascular cryptogams - with vascular tissue but not seeds

• Spermatophytes - both vascular tissue and seeds

• Charophytes - green algae that began adapting to land 

Evolutionary strategies to survive the occasional drying of bodies of water:

• Drought-resistant spores

• Large, compact, multicellular bodies retain water better than small unicellular/filamentous bodies

• Waterproofing cuticles would be advantageous

• Coordination of gamete production with moisture for swimming sperm

Gamete and spore mother cells needed protection from dryness.

• Resulted in the grouping and protection of spore and gamete mother cells into the sporangia characteristic of all embryophytes

  • More massive than those of algae

  • Protected by a layer of sterile cells

Environment became selective for mutations that produced an upright body that could grow into brighter light.

• Production of pollen and seeds eliminates the need for environmental water for reproduction.

• Vascular tissue, especially phloem, also made feasible the evolution of truly heterotrophic tissues – roots, meristems, and organ primordia.

Nonvascular plants are technically embryophytes that do not have vascular tissue.

As embryophytes, they have multicellular sporangia and gametangia.

All mosses and many liverworts have leafy stems similar to small versions of flowering plants.

Almost exclusively terrestrial and have a cuticle body covering, and many have stomata.

Life cycle with an alternation of heteromorphic generations

Being small and simple provides great selective advantage in certain habitats.

They are often treated as three distinct divisions:

• Division Hepatophyta (Liverworts)

• Division Bryophyta (Mosses)

• Division Anthocerophyta (Hornworts)

Ubiquitous - occurring in all parts of the world and in almost every environment

Perennial - life cycle is more than 2 years

Large and photosynthetic; supports sporophyte

Gametophyte Generation

• The leafy stems are technically known as gametophores and form dense mounds.

• All moss stems have leaves but because they are parts of a gametophyte, not a sporophyte, they are not homologous with those of vascular plants.

Hydroids - cells that make up the innermost cortex; conducts water and dissolved materials. 

Leptoids - resemble sieve cells

Capillary action - through which water is conducted along the stem’s exterior. 

Rhizoids - found at the stem’s base; anchors the stem but do not function in water/mineral absorption

Protonema - filament produced through spore germination, forming gametophyte generation

• Gives rise to multiple gametophores

Gametophore produces gametangia

• Antheridia  - sperm production

• Archegonia - egg production

  • Secretes sucrose to guide sperm towards it and then to the egg, leading to fertilization.

Never an independent, free-living plant.

All moss sporophytes form the zygote and have three basic components.

• Foot - interface with the gametophore

• Capsule - simple sporangium where spores are produced

• Seta - between the foot and the sporangium

None is branched or has leaves, bracts, or buds of any kind

Dehiscence of the sporangium is more complex than the opening of the gametangia.

• Operculum - cap-like lid at the sporangium’s apex; separates from the rest of the sporangium

• Peristome teeth - humidity-dependent; bends inward and opens the operculum when the air’s dry 

•  Calyptera - covers the apex

Critical Factors: its small size and lack of conducting tissues.

• Lack of vascular tissues can lead to the stem and leaves’ desiccation.

They live in moist habitats mainly due to their inability to retain water.

Alternation of heteromorphic generations is present.

Sporophyte is less conspicuous and is dependent on the gametophyte.

Hepatic gametophytes are divided into two basic groups:

• Leafy liverworts

• Thallose liverworts

May either be bisexual or unisexual

• Antheridiophore is stalked and umbrella-shaped, produced by a male gametophore

• Archegoniophores have a set of drooping projections 

  • If sperm cells are carried to the archegoniophore via raindrop splashing, they swim into the archegonium neck and fertilize the egg.

  • The zygote is retained on the gametophore and grows into a small sporophyte.

Basic morphology is similar to mosses.

• Foot, seta, and sporangium covered in calyptra.

Elaters - cells differentiate into these rather than undergoing meiosis.

Small, inconspicuous thalloid plants growing on moist soil

Resembles thalloid liverworts excluding oil bodies

Single large chloroplasts are found in each cell

• In other non-algal plants, these are small plastids instead

3-4 protonema cells are produced before the gametophyte phase is established

Parenchymatous – succulent but brittle

Nostoc cyanobacteria form a symbiosis with hornworts, invading its mucilage chambers and giving nitrogen compounds.

Gametangium development  in hornworts is distinctive

• Archegonia does not completely surround the egg as other embryophytes’ do.

• Zygote divides longitudinally; while in mosses and liverworts, they divide transversely.

Sporophytes of hornworts are different from mosses or liverworts.

• Foot is embedded in gametophore tissue

• No seta or discrete sporangium

Despite it being chlorophyllous, it dies when separated from the gametophyte.

Conversion of a monobiontic ancestor into dibiontic plants:

• Monobiontic - only one multicellular form

• Dibiontic - multicellular form in both the sporophyte and gametophyte generations

All living and most fossil plants are dibiontic with an alternation of heteromorphic sporophytes

Genus Cooksonia, earliest fossils of vascular land plants

• Rhynia and Aglaophyton are vascular plants similar to Cooksonia

Had equal dichotomous branching, both branches having equal size and vigor

Ends of the branches were swollen and contained large, multicellular masses of sporogenous tissue surrounded by several layers of sterile cells

Homosporous

Protostele - solid mass of xylem with no pith at the center; present in both

• Endarch Protostele - protoxylem is located in the center and metaxylem differentiates on the outer edge of the xylem mass

• Exarch Protostele - metaxylem is located in the center of the xylem mass and protoxylem on the edges as several groups next to the phloem

Siphonostele - pith is present in the center, as occurs in the stems of ferns and seed plants

Similar to rhyniophytes except:

• Sporangia were lateral, not terminal

• Sporangia opened transversely along the top edge

• Xylem was an exarch protostele

These grew as small bunches with cuticle, ordinary epidermal cells, and stomata on upper portions of naked stems

Lateral sporangia and exarch protosteles; similar to zosterophyllophytes

Some had smooth surfaces, others had enations

• Outgrowths that ranged from small to long, thin scales

• Increases photosynthetic surface area of the plants

Evolution of true roots which allowed:

• Firm anchorage

• Efficient absorption

• Grow to tremendous size

Cones or Strobili

• Clusters of sporangia

• Either homosporous or heterosporous

Lycopodium - small herbs with prostate rhizomes that have true roots and short upright branches; homosporous

Selaginella - heterosporous; megagametophyte develops within megaspore wall

• Ligule - small flap of tissue on the upper surface of their leaves

Isoetes - genus of small, unusual plants; body consisting of small corm-like stems with roots attached below and leaves above.

Trimerophytes had an unequal branching in which one stem was more vigorous; overtopping

Pertica displays pseudomonopodial branching, having a single main trunk rather than a series of dichotomies

Positioning of branches became more regular and controlled

Existed until the Upper Devonian Period and evolved into the ancestors of ferns and seed plants

Euphyllophytes are united by three synapomorphies:

• Roots have exarch xylem

• Megaphylls

• A 30-kilobase inversion in the large single-copy region of their plastid DNA

Euphyllophytes’ sister clades:

• Monilophytes (ferns/fern allies)

• Lignophytes (woody plants)

Division Arthrophyta (Sphenophyta)

• Genius Equisetum (Horsetails/Scouring Rushes)

• Aerial stems have a jointed structure, with a whorl of fused leaves at the nodes

• Stems are siphonosteles (w/ pith)

Reproductive structures are specialized: sporangia in groups of 5-10 in umbrella-shaped sporangiophore

Early arthrophytes have true monopodial growth

Consists of groups: Marattiales, Ophioglossales, and Psilotales

Leptosporangiate 

Ubiquitous

Perennial and herbaceous

Stem’s vascular system is an endarch siphonostele

Leaf trace diverges from the siphonostele ata each node forming a leaf gap 

• Segment of the vascular cylinder that’s just parenchyma

Fiddlehead - tightly coiled young leaf caused by a distinct apical cell of fern leaf primordia

Sori - on the leaf’s underside; clusters of sporangia where meiosis occurs

Gametophytes - heart-shaped or ribbon-shaped photosynthetic structures with rhizoids

• Forms once spores germinate

Contains the simplest of all living vascular plants

Unusual short, branched cylinders of gametophytes (less than 2 mm in diameter)

Traditional and informal term for the plants discussed

They lack seeds, flowers, fruits

Vascular cryptogams are not grouped together formally because cladograms are based on synapomorphies and not a lack of features.

Seed-producing plants that have no flowers and no leaves, but rather cones and needles.

A disadvantage of alternation, independent heteromorphic generations is that the new sporophyte, while developing from the zygote, is temporarily dependent on a tiny gametophyte for its start in life.

It would be advantageous if the embryo could use the photosynthetic and absorptive capacity of the leaves and roots of the previous sporophyte.

For this reason, the megagametophyte is retained inside the maternal sporophyte.

Evolution of seeds was preceded by evolution of a vascular cambium.

Cells in the cambium undergo radial longitudinal divisions, thus, growth in circumference with accumulation of wood.

Cambium arose just once, in one group of plants that then gave rise to a monophyletic group of woody plants, the lignophytes.

Shortly afterward, seeds originated, establishing the seed plants, spermatophytes.

The gymnosperms are those plants with “naked ovules,” that is, ovules located on flat sporophylls, like pine cones.

The divisions of living seed plants are:

• Cycadophyta

• Coniferophyta

• Ginkgophyta

• Gnetophyta

• Magnoliophyta (the flowering plants)

Cycadophyta, Coniferophyta, Ginkgophyta, and Gnetophyta are gymnosperms.

Angiosperms are flowering plants.

Synapomorphies:

• Wood and seeds

A third group to evolve from trimerophytes, now extinct.

The vascular cambium that evolved in progymnosperms could function indefinitely, producing large amounts of both secondary xylem and phloem.

Although progymnosperm wood was similar to that of conifers, the two groups must be kept separate because progymnosperms did not have seeds.

Although leaves and wood of progymnosperms were quite advanced, their reproduction was remarkably simple.

Contains more relictual progymnosperms (e.g. Aneurophyton, Protopteridium)

Proteokalon, Tetraxylopteris, Triloboxylon, and Eospermatopteris.

They varied in stature from shrubs (Protopteridium, Tetraxylopteris) to large trees, up to 12 m tall.

The primary xylem of their stems was a protostele like that of rhyniophytes and trimerophytes.

Archaeopteris was a more derived progymnosperm.

Stems had a siphonostele, having pith surrounded by a ring of primary xylem bundles, much like modern conifers and dicots.

Reproduction was heterosporous, and megaspores were released from sporangia.

No seed production.

The megasporangium was surrounded by a layer of tissue, an integument.

There was also a micropyle, a hole in the integument that permitted the sperm cells to swim to the egg.

As megasporangia evolved into ovules with integuments, other telones on nearby branches became modified into cupules (similar to carpels in flowering plants)

Simultaneously, microspores were evolving into pollen grains.

Space at the top of the megasporangium became a pollen chamber.

As megasporangia fused with integuments, other nearby telomes modified into cupules, which may have after given rise to the carpal.

Progymnosperms gave rise to another line of gymnospermous plants in addition to the conifers, the cycadophytes.

These are classified into three divisions:

• Pteridospermophyta (seed ferns, all extinct)

• Cycadophyta (cycads, extant)

• Cycadeoidophyta (cycadeoids, all extinct)

Not all seed ferns are closely related to each other.

Thought to have evolved from the Aneurophytales b/c the earliest seed ferns had a three-ribbed protostele.

Manoxylic wood: softer, large amount of axial parenchyma, less tracheids as in cycads

Seed ferns were any woody plants with fern-like foliage that bore seeds instead of sori. Leaves of seed ferns were similar to those of true ferns in overall organization – large, compound, and planar.

The most diverse group and all are trees of moderate to gigantic size.

Conifer leaves are always simple needles or scales, and most are perennial.

Pycnoxylic wood: hard with little or no axial parenchyma, more wood or xylem.

Wood of modern conifers lacks vessels, is composed completely of tracheids, and their phloem lacks sieve tubes

In pines, annual rings, spring, and summer wood are all visible.

Resin canals run vertically among the tracheids and horizontally in the rays.

The venation of conifer leaves is often simple, with just one or two long veins running down the center of a needle-shaped leaf or several parallel veins in scale-shaped leaves.

Transfusion tissues

• Circular bordered pits of tracheids

Pines, like other conifers, have two types of shoot:

• Tiny papery leaves in long shoots

• Produce long needle leaves in the L.S. axils – short shoots

Monopodial trees

All conifers have pollen cones (staminate) and seed cones (ovulate), most woody

Monoecious 

Pollen cones are simple cones, with a single short unbranched axis that bears microsporophylls

Seed cones are more complex cones; compound cones, each consisting of a shoot with axillary buds

The short axis of seed cones bears leaves called cone bracts rather than sporophylls.

Each bract has an axillary bud that bears megasporophylls

Megasporophylls are laterally fused, forming an ovuliferous scale.

Inside each megasporangium, a single large megaspore mother cell undergoes meiosis, with three of the resulting cells degenerating and only one surviving as the megaspore

Conifer pollen arrives before the egg is mature, and more than a year may pass between pollination and fertilization.s vv

Have non-motile sperms

Siphonogamy: pollen tube digests its way to the megasporangium to deliver sperms to the archegonia. 

Pollen Tube - exosporing, tube-like extension from pollen grain

The pollen tube is haustorial (parasitic, feeding off tissues) in Gymnosperms while in cycads & Ginkgo sperm delivered to fertilization chamber, where sperm swims to archegonium = zooidogamy.

In conifers (incld. Gnetales) pollen tube grows directly to the archegonium = siphonogamy

2-3 eggs can be fertilized but only one develops into an embryo, other dies

Zygote first forms suspensor cells penetrate deep into the megagametophyte; proembryo develops into the embryo

Female gametophyte grows and acts as an endosperm; many cotyledons.

Internal structure is similar to seed ferns:

• Thick cortex with secretory ducts that surround a small amount of manoxylic wood

Cycad foliage leaves do not bear ovules

Resemble stout palms

Have single pithy stems with little wood

Have a crown of large, pinnate leaves

Show circinate venation like ferns

Cycads produce seed cones and pollen cones, each on separate plants

Seed cones are variable; those of Cycas revoluta considered the most relictual

Cycads produce seed “cones” (aggregate of megasporophylls) and pollen cones, each on separate plants (dioecious)

Seed cones are variable, with those of Cycas revoluta usually considered the most relictual.

Cycads, unlike other seed plants, have motile sperm.

These are large, up to 300 micrometers 

The large motile sperm cells of cycads with hundreds of flagella

Although cycadophyta was a much larger group, currently, it contains 9-10 genera and approx. 100 species

Almost all are tropical with an unusual distribution

All extinct

Had vegetative features identical to cycads

Individual cones contained both microsporophylls and megasporophylls

The division contains a single living species, Ginkgo biloba

Its wood is like that of conides – lacks vessels, and axial parenchyma; pycnoxylic wood

It has broad leaves with dichotomously branched veins like seed ferns, not reticulate venation like dicots

Short and long shoots

Dioecious and gymnospermous, but cones are not produced

The megasporangiate trees produce seeds; the outer fleshy layer of the seed emits butyric acid, which has a putrid odor that is difficult to tolerate

Ginkgo biloba seeds develop from ovule pair

A seed at maturity consists of an embryo and endotesta. The nutritive tissue and the seed coat is made up of a hard inner layer (sclerotesta) and a fleshy, yellow to orange-colored layer or sarcotesta.

Pollen cones and short shoot is catkin-like; each sporangiophore

• Has 2 microsporangia

All three genera (Gnetum, Ephedra, Welwitschia) are unusual in being gymnosperms with vessels in their wood with circular bordered pits

Heterosporous; gnetophytes pollen cones are compound and contain small bracts (like staminate flower)

Compound seed cones with bracts, integument and sporophyll

Welwitschia mirabilis: indeterminate growth from basal meristem, only 2 long leaves; found in deserts 

All extant species are woody

Have non-motile sperms: siphonogamy

• Pollen tube delivers sperms to the archegonia

Perforation of the terminal walls of some of the tracheids with circular bordered pits to form vessels

One Ephedra sperm (haploid) fertilizes an egg cell (haploid) producing a diploid embryo.

• A second sperm nucleus fuses with a female gametophyte nucleus, producing another embryo

• Only one embryo matures to become a seed

Gnetum gnemon (and Welwitschia) does not form egg cells; instead, as a product of meiosis, it forms egg nuclei that are free in the female gametophyte

• Two separate fertilizations form two diploid embryos

• Only one becomes seed

Subsequent to fertilization, several female Gnetum nuclei fuse, developing polyploid, embryo-nourishing tissue that is the functional equivalent of endosperm but of different origin

Conversion of gymnospermous sporophylls into stamens and carpels, resulting in the formation of flowers

Double fertilization

• Zygote

• Endosperm

Evolutionary changes involved in the conversion of gymnosperms to angiosperms

• Double fertilization 

• Ability to produce bisexual flowers

• Appearance of vessel elements

• Appearance of sieve tube

• Ancestral flowering plants were woody perennials

• Annual growth habit

Other derived features of angiosperms are fusion of carpals into a pistil, fusion of petals (sympetaly), and floral zygomorphy

Most consumed plants are angiosperms

Wind-pollinated trees were considered “most relictual living flowering plants”

Small and simple flowers without sepals and petals

Recent DNA studies revealed this is a derived condition and evolved several times in various clades

Approx. 100 years ago, C.E. Bessey developed the hypothesis of the ranalean flower, in which a Magnolia-type flower was thought to be relictual

Such a flower is generalized, it contains all floral parts

Angiosperms are monophyletic; transition from gymnosperms occurred during Jurassic and Lower Cretaceous Periods of the Mesozoic Era.

With living descendants of several groups

• Originated while angiosperms were still a young clade

Consists of:

• Amborellaceae

• Nymphaeaceae

• Austrobaileyales

• Magnoliid clade

  • Magnoliales & Laurales

  • Canellales & Piperales

With characteristics that make them “in-between”

Members undergone considerable evolutionary changes

Amborella - woods have tracheids no vessels, and little parenchyma

Magnoliaceae - trees with wood similar to gymnos; pollen grains uniapertuarete (basal angiosperms and monocots)

Amborella trichopoda (Amborellaceae)

Nymphaea spp. (Nymphaceae)

Kadsura marmorata, Illicium sp. (Austrobaileyales)

Magnolia grandiflora, M. angatensis (Magnoliales)

Laurus nobilis, Persea americana (Laurales)

Drymis winteri, Tasmannia piperita (Canellales)

Aristolochia baetica, Pepperomia lanaoensis (Piperales)

All monocots with no ordinary secondary growth

• Anomalous growth only

• Possible ancestors were herbs with no vascular cambium

• Believed to have arisen from early angiosperms approximately 80-100 million years ago

Gynoecia with carpels (usually 3) that are free or fused

• Tepals - very similar perianth members

Parallel venation of monocot leaves

• Adaptation for submerged plants

• Basal and marginal meristem types

Lilium sp.

Mostly aquatic herbs, found in swamps and marshes

• Submerged species are sea-grasses

• Loss of stomata

• With air chambers

• No lignified fibers

Relictual members with large, showy flowers

• Submerged flowers lack perianth

Family Araceae: spathe and spadix inflorescence

Petaloid monocots

Presence of spots/lines on petals or nectaries formed at bases of tepals or stamens

Numerous members: evolution as diversification (extremely diverse in morphology

Fused carpels with septa and septal nectaries

One family: Dioscoreaceae

Vines and climbers

Produces starchy “tubers”

Petiolate, broad leaves with reticulate venation

Synapomorphies

• With unique type of epicuticular wax

• Walls with unusual hemicellulose and UV-fluorescent compounds

• Pollens contain starch

• Molecularly supported as a distinct clade

Palm trees, shrubs

3,500 species

Solitary trunk

Leaves only at shoot apex

Feather palms (pinnate); fan palms (palmate)

Inflorescence axillary, bracteate panicle or spile of solitary flowers

Unisexual or bisexual

Economic importance: Cocos nucifera, Phoenix dactylifera

Grasses, sedges, bromeliads

Either insect- or monoulcerate pollen grains that are typically wind-pollinated flowers

With large, showy flowers pollinated by insects, birds, bats

Derived features:

• Fused sepals forming a tube

• Bilaterally symmetrical flowers

• Inferior gynoecium

• Petiole/leaf becoming flattened and broadened were selectively advantageous

Family ZIngiberaceae

• Broad leaves with flattened petiole

• Economically important species

Pollen grains with three germination pores (tricolpate)

Flower parts in whorls

Stamens with defined filament (stalk) and anther

Believed to be clades that diverged at early stages in eudicot evolution

Flowers with little fusion of parts

Notable for its water-soluble pigment, betalains

Little endosperm development

• Nucellus cells form a nutritive tissue – perisperm

Phloem plastids with deposits of fibrous protein

Posses trinucleate pollen upon release

Free-central or basal placentation of seeds

Small order of highly modified hemiparasitic to fully parasitic plants

Family Santalaceae & Loranthaceae

Rosids: bitegmic, crassinucellate ovules

Asterids: unitegmic, tenuinucellate ovules

Has no clear apomorphies; very diverse

• Superosids APG IV, 2016

• Eurosids I (Fabids)

• Eurosids II (Malvids)

5 orders = 75% of total identified members

• Fabales (legumes)

• Myrtales (eucalyptus, Melastoma, Medinilla)

• Malpighiales (euphorbs e.g. poinsettia; Passiflora)

• Rosales (roses, elms, marijuana)

• Sapindales (mango, citrus, maples)

Most derived of the eudicots

Many with iridoid compounds

Apomorphic characters:

• Sympetalous flowers (petals are fused together into a tube)