Plantae Vocab & Concepts

Accessory Fruit

•  A fruit in which part of the fruit is formed from tissues outside of the ovary (i.e. pomes).

Aggregate Fruit

• A fruit that results from several independent carpels on a single flower (i.e. raspberries).

Alkaloid

• Type of secondary metabolite with the widest range of pharmacological activity; includes many frequently used drugs and medicines (caffeine, cocaine, codeine, nicotine, quinine, morphine, heroine, etc).

Alternation of Generations

• The succession of multicellular haploid and diploid phases in some sexually reproducing organisms, notably plants.

  • A diploid spore-forming organism gives rise to a haploid gamete-forming organism

  • When haploid gametes fuse, a diploid individual is formed

  • Both stages are multicellular and undergo mitosis.

Anther

• A pollen-bearing portion of the stamen of a flower.

Antheridia

• The multicellular structure that produces the sperm in nonvascular land plants and ferns.

Apical Meristems

• The meristem at the tip of a shoot or root (SAM & RAM); responsible for a plant’s primary growth (growing longer).

Archegonia

• The multicellular structure that produces eggs in nonvascular land plants, ferns, and gymnosperms.

Auxin

• In plants, a hormone (the most common being indole-3-acetic acid) that regulates growth and various aspects of development.

  • Important in root initiation, apical dominance, & phototropism

  • Auxin molecules move towards the shaded side → Auxin stimulates cell elongation, causing the shaded side to grow at a faster rate

Bifacial Vascular Cambium (BVC)

•  In plants, a lateral meristem that gives rise to secondary xylem and phloem.

  • Results in plant growing wider

  • When a BVC cell divides, it produces either a new xylem cell toward the inside of the stem or root, or a new phloem cell toward the outside 

  • Secondary xylem is wood

Carpel

• The organ of the flower that contains one or more ovules. It is a FEMALE reproductive organ.

  • Consists of three main parts: stigma, style, & ovary

Central Cell

•  Refers to a specific cell within the ovule of a flowering plant. 

  • Typically contains two nuclei, and after pollination, one of these nuclei fuses with a sperm cell, leading to the formation of a triploid cell. 

  • This triploid cell contributes to the development of the endosperm, a tissue that provides nutrients to the developing embryo.

Chlorophyll

• Any of several green pigments associated with chloroplasts or with certain bacterial membranes; responsible for trapping light energy for photosynthesis.

Chloroplast

• The active sites of photosynthesis in a plant cell; they are the product of a symbiosis between a eukaryote & cyanobacteria.

  • Have their own haploid DNA

  • Thylakoid membranes

  • Use a combination of pigments, protein complexes, & enzymes to capture light energy & transform it into chemical energy

Collenchyma

• A type of plant cell, living at functional maturity, which lends flexible support by virtue of primary cell walls typically thickened at the corners.

  • Lacks lignin (hence alive)

Companion Cell

• In angiosperms, a specialized cell found adjacent to a sieve tube element - it keeps the sieve tube alive. It is a component of the phloem.

Determinate Growth

• A growth pattern in which the growth of an organism or organ ceases when an adult state is reached, characteristic of most animals and some plant organs (i.e. leaves).

Diploid

• Having a chromosome complement consisting of two copies (homologs) of each chromosome. Designated 2n.

Double Fertilization

• In angiosperms, a process in which the nuclei of two sperm fertilize one egg. One sperm’s nucleus combines with the egg nucleus to produce a zygote, while the other combines with the same egg’s two polar nuclei to produce the first cell of the triploid endosperm (the tissue that will nourish the growing plant embryo).

Embryo

• A young plant sporophyte while it is still contained within a protective structure such as a seed.

Filament

• In flowers, the part of a stamen that supports the anther.

Flower

• The sexual (reproductive) structure of an angiosperm.

Fruit

• In angiosperms, a ripened and mature ovary (or group of ovaries) containing the seeds. Sometimes applied to reproductive structures of other groups of plants.

Gametangia

• Any plant or fungal structure within which a gamete is formed.

Gametes

• The mature sexual reproductive cell: the egg or sperm.

Gametophyte

• In plants and photosynthetic protists with alternation of generations, the multicellular haploid phase that produces the gametes.

Gibberellins

• A class of plant growth hormones that play roles in stem elongation, seed germination, flowering of certain plants, and other processes.

  • Important in stem elongation & fruit growth 

Haploid

• Having a chromosome complement consisting of just one copy of each chromosome; designated 1n or n.

Heterospory

• Producing two different (size) types of spores, one of which gives rise to a female megaspore and the other to a male microspore. 

Homospory

• Producing a single type of spore that gives rise to a single type of gametophyte, bearing both female and male reproductive organs.

Hydroids & Leptoids

• Hydroids are specialized tissues found in the vascular tissues of certain plants, primarily in the phylum Bryophyta, that conduct water. Leptoids are also specialized tissues found in bryophytes that conduct sugar.

Indeterminate Growth

• An open-ended growth pattern in which an organism or organ continues to grow as long as it lives; characteristic of some animals and of plant shoots and roots.

Integuments

• A protective surface structure. In gymnosperms and angiosperms, a layer of tissue around the ovule that will become the seed coat.

Lateral Meristems

• Either of two meristems, the vascular cambium and the cork cambium, that give rise to a plant’s secondary growth.

Lycophyll/Microphyll

• Lycophylls are reduced megaphylls found in lycophytes that are not synonymous with true microphylls. Microphylls are the true microphylls and they only evolved in lycophytes.

Megagametophyte

• In heterosporous plants, the female gametophyte; produces eggs.

Megaphyll

• The generally large leaf of a fern, horsetail, or seed plant, with several to many veins.

Megaspore

• In plants, a haploid spore that produces a female gametophyte.

Meiosis

• The division of a diploid nucleus to produce four haploid daughter cells. The process consists of two successive nuclear divisions of a cell that has undergone only one cycle of chromosome replication. In meiosis I, homologous chromosomes separate but retain their sister chromatids. The second division, meiosis II, is similar to mitosis, in which sister chromatids separate.

Meristem Cells

• Undifferentiated, actively dividing cells found in the growing tips of plants and in areas of the plant where growth occurs. These cells are responsible for the plant's primary growth, enabling the plant to increase in length and produce new organs, such as leaves, stems, and roots. 

Microgametophyte

• In heterosporous plants, the male gametophyte; produces sperm.

Microphyll

• A small leaf with a single vein, found in club mosses and their relatives.

Microspore

• In plants, a haploid spore that produces a male gametophyte.

Mitosis

• Nuclear division in eukaryotes leading to the formation of two daughter nuclei, each with a chromosome complement identical to that of the original nucleus. With cytokinesis, makes up M phase of cell cycle.

Multiple Fruit

• A fruit that develops from several carpels of multiple flowers.

Nodes

• In plants, a (sometimes enlarged) point on a stem where a leaf is or was attached. They are collections of meristematic tissue from which leaves or other organs grow.

Parenchyma

• A type of relatively unspecialized plant cell without secondary walls.

  • No lignin - ALIVE

  • Bulk of metabolism occurs here

Petal

• In an angiosperm flower, a sterile modified leaf, nonphotosynthetic, frequently brightly colored, and often serving to attract pollinating insects.

Phloem

• In vascular plants, the vascular tissue that transports sugar and other solutes from sources to sinks.

  • Comprised of sieve tube elements and companion cells

  • ATP present

Plasmodesmata

• In plants, membrane-lined channels that extend through the cell walls and connect the cytoplasms of adjacent cells (cell-cell junctions).

Pollen

• In seed plants, the male gametophytes that contain the male gametes (microspores). Pollen delivers sperm directly to the egg (Dispersal Stage). It is so reduced that the antheridium is lost; nuclei function as sperm.

Pome

• A type of fruit that develops from the ovary of a flower and typically has a thick, fleshy outer layer surrounding the seeds. Examples include apples and pears.

Primary Growth

• In plants, growth that is characterized by the lengthening of roots and shoots and by the proliferation of new roots and shoots through branching (apical meristems). It occurs at the tips & cell division in the SAM & RAM make the plant grow longer.

Rhizome

• An underground stem (as opposed to a root) that runs horizontally beneath the ground.

Root

• The organ responsible for anchoring the plant in the soil, absorbing water and minerals, and producing certain hormones. Some roots are storage organs. 

  • Consists of three main parts: root apical meristem, root cap (protects the RAM), & root hair

Root Apical Meristem

• A group of cells at the apex of the root that gives rise to the organs of the root.

Root Cap

• A thimble-shaped mass of cells, produced by the root apical meristem, that protects the meristem; the organ that perceives the gravitational stimulus in root gravitropism.

Root Hairs

• A long, thin process from a root epidermal cell that absorbs water and minerals from the soil solution.

Sclerenchyma

• A type of plant cell with heavily thickened cell walls. The principal types of sclerenchyma cells are fibers and sclereids.

  • Dead at maturity

  • Provides strength/support to plant

  • Lignin in cell walls 

Secondary Growth

• In plants, growth that contributes to an increase in girth/width (lateral meristems). Seed plants have secondary growth by cell division in the bifacial vascular cambium (BVC); this results in the plant growing wider (new xylem or phloem produced).

Secondary Metabolite

• Compounds produced by plants (also fungi & bacteria) that are not part of growth, development, or reproduction (not needed for basic cellular metabolism). They are not essential to survival but contribute to overall survivability (typically has an antiherbivore/antiparasitic function).

Seed

• A fertilized, ripened ovule of a gymnosperm or angiosperm. Consists of the embryo, nutritive tissue, and a seed coat. All seed plants make seeds.

Sepal

• One of the outermost structures of the flower, usually protective in function and enclosing the rest of the flower in the bud stage.

Sieve Tube

• The characteristic conducting cell of the phloem in angiosperms, which contains cytoplasm but relatively few organelles, and whose end walls (sieve plates) contain pores that form connections with neighboring cells.

  • Kept alive by companion cells

Sori

• A spore-producing structure on the underside of a fern frond.

  • Brown in color

Sporangium

• In plants and fungi, any specialized structure within which one or more spores are formed.

Spore

• Any asexual reproductive cell capable of developing into an adult organism without gametic fusion. In plants, haploid spores develop into gametophytes, diploid spores into sporophytes. 

Sporophyte

• In plants and protists with alternation of generations, the diploid phase that produces the spores.

Stamen

• A MALE (pollen-producing) unit of a flower, usually composed of an anther, which bears the pollen, and a filament, which is a stalk supporting the anther.

Stomata

• A small opening in the plant epidermis that permits gas exchange; bounded by a pair of guard cells whose osmotic status regulates the size of the opening.

  • Present on leaves

Stroma

• The fluid that surrounds the grana in the chloroplast.

Terpene

• Secondary metabolite that is strongly fragrant, often resinous, & typically used to deter herbivores in plants. Aromatic oils (lavender) & THC (active compound in marijuana) are examples.

Thylakoid

• A flattened sac within a chloroplast. Thylakoid membranes contain all of the chlorophyll in a plant, in addition to the electron carriers of photophosphorylation. Thylakoids stack to form grana.

Tracheid

• A type of tracheary element found in the xylem of nearly all vascular plants, characterized by tapering ends and walls that are pitted but not perforated. It is responsible for transporting water.

  • First type of xylem tissue that evolved

  • Has lignified secondary cell walls

  • Dead at maturity

Trichome

• A hair-like structure found on the surface of plants, serving functions such as protection against herbivores, secretion of substances, temperature regulation, and absorption of water and nutrients from the environment. 

Vessel Element

• A type of tracheary element with perforated end walls; found only in angiosperms and gnetophytes.

  • Evolved in angiosperms and gnetophytes

  • Larger & connected end-to-end (similar to a boba straw)

  • Has lignified secondary cell walls

  • Dead at maturity

Waxy Cuticle

Provides a coating of waxy lipids that retards water loss in plants.

Xylem

•  In vascular plants, the tissue that conducts water and minerals; xylem consists, in various plants, of tracheids, vessel elements, fibers, and other highly specialized cells.

  • NO ATP

  • Roots to Shoots

Zygote

• The cell created by the union of two gametes, in which the gamete nuclei are also fused. The earliest stage of the diploid generation.

  • Fertilized egg

Features That Allowed Plants to Live on Land

• Waxy Cuticle

• Protected Embryos

• Airborne Spores with Sporopollenin (prevents desiccation)

• Gametangia

• Sporophyte

Plants & Music

• Several classical works use plants as themes, such as the “Waltz of the Flowers” from the Nutcracker Suite.

• 1960’s: Several famous folk & protest songs had flowers & trees as central themes, emphasizing a connection to nature.

  • “Where Have All the Flowers Gone?” &”Scarborough Fair”

• Several songs inspired by marijuana, especially Reggae music.

• Multiple songs in the 70’s and 80’s were inspired by cocaine - most focused on problems with addiction.

Plants & Movies

• Plants as villainous and dangerous; can be detrimental health if utilized wrongly:

  • Invasion of the Body Snatchers

  • Attack of the Killer Tomatoes

  • Little Shop of Horrors

  • Casino Royale

• Plants as signs of life:

  • Wall-E

  • The Martian

Advantages of Sporophyte Dominance

• Enhanced Dispersal:

  • Spores from sporophytes have wider dispersal, aiding in colonization.

• Structural Advantage:

  • Sporophytes are larger and structurally complex, enhancing competitiveness (a lot bigger/taller, so more photosynthesis).

• Efficient Reproduction:

  • Sporophyte dominance results in the production of numerous spores.

Vascular Plant (Tracheophyte) Synapomorphies & Other Traits

• Synapomorphies:

  • Branching, independent sporophyte

  • Roots

  • Tracheids

• Other Traits:

  • Dominant Sporophyte - the gametophyte is small and lives independently

  • Lignified Vascular Tissue (Xylem & Phloem)

Dermal Tissues

• Form the epidermis & secrete waxy compounds that protect the plant from desiccation.

Vascular Tissues

• Xylem & Phloem

• Transport water, minerals, and sugars

Ground Tissues

• Fill in the inner space of the plant and perform metabolic, support, and storage functions.

What are the possible advantages of producing two types of spores? What stage of the life cycle do spores develop into in land plants?

• Possible Advantages: More Specialization + Greater Spore Dispersal

• Development in Sporophyte Stage

Euphyllophyte Synapomorphies

• Megaphylls

• Overtopping Growth

• DNA Chloroplast Inversion (order of genes in chloroplast DNA is flipped)

Overtopping Growth

• The type of growth where there is uneven growth of the stem; it contrasts with the dichotomous branching of lycophytes.

How does the life cycle of a fern compare to that of moss? Explain how the dominance and nutritional independence of the gametophyte and sporophyte has changed.

• Moss: Gametophyte Dominant - the sporophyte is attached to the gametophyte and cannot live on its own (nutritionally dependent)

• Fern: Sporophyte Dominant - the sporophyte is its own separate entity from the gametophyte and can live on its own (nutritionally independent)

Are the “microphylls” of Psilotum homologous to the microphylls of lycophytes? What specific evidence would you use to support your argument?

• NO, they are NOT homologous

• Evidence: DNA Chloroplast Inversion

Psilotum (Whisk Ferns)

• Genus of monilophytes with reduced roots, dichotomous branching, sporangia at nodes, & “microphylls”

Equisetum (Horsetails)

• Characterized by having a hollow stem with a whorl of reduced leaves; woody strobili at their tips

Seed Plant Synapomorphies

• Seeds

• Pollen

• Heterospory

• Secondary Growth

Seed Plant Gametophyte Retention

• Gametophyte is retained on and nourished by the sporophyte

• Reduction of the gametophyte is a trend in plant evolution

Where are pollen and seeds in the life cycle?

• Pollen: Microgametophyte Stage (n)

• Seeds: Embryo (2n)

Why do most leaves have determinate growth?

• No meristematic cells to generate growth (i.e. no nodes)

Gardeners encourage lateral growth in plants by removing apical buds on branches. Why is this effective?

• Cutting off tips —> Reduces concentration of Auxin —> Signal does not get to other meristems —> Plant starts to grow

• With less auxin reaching them, the lateral buds are released from growth inhibition. This allows them to start actively growing outwards and increasing lateral branching.

What is a peanut? Can you identify all the layers?

• Peanut = Fruit

• Brown Wrapper = Seed Coat

• Outer Shell = Fruit