Houseplant Term Glossary


Acidic — Having a pH that is lower than 6.5. Acidic soil is generally made up of tree bark or peat moss; the acidity can be lowered by adding limestone powder.

Adventitious Root — Roots that come from above ground, such as from stems or leaves. Especially common on plants that grow from corms, tubers, or rhizomes.

Aerial/Air Root — A root that emerges from the plant’s stem above the soil and either goes into the soil, or attaches itself to something else for support.

Air Layering — A method of propagation where damp sphagnum moss is wrapped around around a branch, sometimes a small wound is made where the moss is placed, and then covered with something like plastic wrap. Air layering can also be accomplished by bending a branch down to the soil line, holding it in place, and placing potting mix over it.

Alkaline — Having a pH that is higher than 7. Alkaline soil is generally made up on soil from areas that contains a lot of limestone, or has low rainfall. You can make the soil more acidic by adding sulphur.

Annual — A plant that is grown from seed, and will go through the entire growing process and reproduction within a year.

Anther — The male part of the flower that contains the pollen.

Areole — The small areas on a cactus where the spines or hairs grow. These areas are generally raised or depressed.

Aroid A name that is commonly given to plants in the Arum family, Araceae.

Arum — A family of monocotyledonous, a type of plant that only has one seed leaf, that produce flowers on a type of inflorescence called a spadix. This spadix generally goes along with, or is partly surrounded surrounded by, a spathe.


Bonsai — Japanese art of growing a decorative miniature form of a full sized tree or shrub.

Bract — A specialized, modified leaf that is usually located beneath the reproductive part, such as a flower, inflorescence, or cone scale. These often look different than the rest of the leaves on the plant.

Bulb — Round, underground storage root. For more information about bulbs click here.


Cachepot — A decorative pot or container that you place a smaller pot containing a plant inside of.

Callus — Cells that cover the wound on a plant to prevent loss of sap and to prevent water, pests, fungi, or bacteria from entering.

Caudex — Plump, swollen trunk, above-ground roots, or stem. For more information about caudiciform plants click here.

Caudiciform —Type of plant that have a caudex. For more information about caudiciform plants click here.

Caudices — The plural of caudex.

Cholorphyll — The molecule, or pigment, in plants that makes them green; it is used to convert sunlight into energy via photosynthesis.

Chlorosis — Yellowing of the leaves.

Coir — Coconut fiber that is collected from the husks of coconuts. For more information on potting mix additives click here.

Corm — Squat, underground storage root. For more information about corms click here.

Cotyledon — The embryonic leaf that you see emerge from a germinated seed.

Crown — A group of stems that are closely attached either above or below the soil and radiate from the center. A good example is the African violet.


Deadhead — Removal of dead or dying flowers that encourages the plant to produce more blooms.

Deciduous — A plant that naturally goes through a cycle in which it drops all of its leaves, goes dormant for a period of time, then regrows the leaves. A good example would be a maple tree.

Distilled Water — Distilled is basically dead water, which means everything in it has been removed through boiling. For more information on the types of water click here.

Dormant — A natural cycle for certain plants in which they either don’t grow, or only grow a tiny amount. Basically like a plant’s version of hibernation.


Epiphyte — Plant that grows on other plants in nooks and get their nutrients and moisture from rain, the humidity in the air, and plant debris that accumulates around them.

Epilith — Plant that grows on rocks and get their nutrients and moisture from rain, the humidity in the air, and plant debris that accumulates around them.

Etiolated — Long, skinny, weak, pale new growth due to lack of light.


Family — A large collection of plants that share botanical characteristics. The plants are put into categories based on similar features, such as shape of the flower, seed groupings, appearance, etc. Plant species are classified in order of genus, family, and group. Every plant family ends with the Latin suffix aceae or ae, such as Araceae, the family that is made up of Aroids.

Frond — The large divided leaf of plants such as ferns or palms.


Genus — A group of related species of plants with similar characteristics.

Glochid — A barbed hair-like spine that grows from areoles on some cacti.

Graft —Where a shoot, twig, branch, etc is put into a cut of a rooted plant. Moon cacti, Gymnocalycium mihanovichii, are often grafted onto Dragon fruit, Hylocerus undatus.

Guttation — Water that is expelled out of the pores on a plant. During the day plants transpire and pull water up through the leaves, and at nighttime when the humidity is higher and the plant’s cells are full of water, guttation occurs to relieve the pressure from the water in those cells.


Honeydew — The waste product from certain pests, which is a clear sticky substance that ants love, and is a good indicator that you have a pest living on your plant. It can also be a perfect place for sooty mold to grow. For more information on pests click here.

Hygrometer — A device used to measure the amount of moisture in the air.


Inflorescence — On a flowering plant, it is the complete cluster of flowers, including bracts, stems, and stalks.


Joint — The area where two part of the plant come together, like where the stem attaches to the trunk.


Keiki — An orchid that is produced asexually and is an exact clone of the mother plant. This happens in Phalaenopsis, Epidendrum, and Dendrobium orchids, and the keiki can even bloom while still attached.

Kokedama — Japanese art of growing plants in a decorative moss-covered ball of potting mix tied together with string or fishing line.


Latex — Milky white sap that comes from certain plants.

Leggy — Another word for an etiolated plant; long, skinny, pale new growth that is stretching towards the light.


Macronutrients — Nutrients that plants need in larger amounts. Specifically N (nitrogen), P (phosphorous), and K (potassium). For more information on the nutrients that plants need and what each one does click here.

Micronutrients — Nutrients that plants need is smaller amounts, such as iron, calcium, magnesium, and copper. For more information on the nutrients that plants need and what each one does click here.

Monocotyledonous — A type of flowering plant that produces a seed with a single cotyledon.


Needles — Thin, pointy secondary leaves on pine trees.

Neem Oil — Oil made from the seed of the neem tree, Azadirachta indica, also called Indian lilac. It is used as an insecticidal spray.

Node — The area on a plant where the leaves connect to the stem.


Oedema (Edema)— Excessive amounts of water being sucked up by a plant that cause cells to swell and rupture.

Offset — A new plant that grows off of the mother plant, and uses it for nutrients and water until it grows its own roots. These are natural clones.

Orchid Bark — This is generally pieces of bark from fir trees that usually comes in three grades, fine, medium, and coarse. For more information on potting mix additives click here.

Ovary — Part of the pistil, the female reproductive organ, of the plant that contains the ovules.

Ovule — Structure in the ovary that when fertilized become seeds.


Peat Moss — This is generally comprised of sphagnum moss that has fallen below the surface of a peat bog, and is therefore decayed. For more information on potting mix additives click here.

Pedicel — In an inflorescence this is the small stalk that carries a flower.

Peduncle — The stem that is supporting the inflorescence or fruit.

Perennial — A plant that lives for more than two years.

Perlite — White additive that is found in potting mixes that looks like styrofoam. For more information on potting mix additives click here.

Pest — An insect that causes harm to plants. For information on identifying types of house plant pests, click here.

Petiole — The part of the plant that connects the leaf to the stem; the leafstalk.

Photosynthesis — The process of turning sunlight into energy.

Phototropism — Plants stretching towards the best source of sunlight.

Pistil — The female reproductive parts of the flower that are centrally located.

Plantlet —A young or little plant.

Pot Bound — Term used for when a plant’s roots have filled up the pot so completely that the plant cannot produce any new growth.

Poisonous Plants — To see a full list of house plants that are poisonous to pets, click here.

Propagation — The process of growing new plants whether it is via seed, cuttings, or from parts of the plant.

Pseudobulb — A above-ground swelling in the stem of certain types of orchids where moisture is stored.

Pumice — This is a volcanic rock that is filled with holes due to gas bubbles getting trapped in lava as it cools. For more information on potting mix additives click here.

Purified Water — This is basically distilled water that has had an extra step added, so the water has nothing it in besides that familiar chemical formula of two hydrogen atoms and one oxygen atom. For more information on types of water click here.


Quadrate — A square frame that is placed to isolate plants, usually a square meter, for study.


Rhizome — Horizontal underground stem that sends out roots. For more information on rhizomes click here.

R/O Water — Reverse osmosis, is a technique that is used to remove minerals and impurities from water, such as chloramine, salts, and heavy metals. For more information on types of water click here.

R/O Water Waste — This water is not suitable for human consumption because it is the waste water that contains all of the chemicals and such that are removed. For more information on types of water click here.

Rooting Hormone — A powder, liquid, or gel that is used to encourage a cutting to produce roots.

Root Rot — A condition caused by too much moisture that causes a plant’s roots to rot and die.

Rosette — Leaves that grow in a circular pattern radiating from the stalk either at ground level, or close to ground level.

Runner — A long thin horizontally growing stem that will produce buds and roots at the tip. The buds will be clones of the mother plant. ie the pups on a spider plant are buds that form on the end of a runner.


Softened Water — Water that has magnesium, calcium, and other metals removed from it using salts. For more information on types of water click here.

Spadix — An spike with inflorescence containing small flowers that is supported on a thick stem.

Spathe — A large leaf-like structure, bract, that is generally colored and encloses the flower clusters, inflorescence, of certain types of plants, ie an Aroid.

Species — The designation that is given to all forms of life that identify them within an establish system of ranks based on its genetic and physical similarities to other forms of life. In other and much simpler terms, it is the descriptive second part of a Botanical name. An example would be the Hoya polyneura, its species is polyneura, which means many nerves, due to how the leaves look. Another good example is the Epipremnum aureum, aka golden pothos, golden devil’s ivy, etc. Aureum means golden, which refers to the golden patches on the leaves.

Spine — A highly modified leaf, or part of a leaf, that is rigid, begins in the axil, and ends in a sharp point.

Spore — A reproductive cell of a bacteria, fungi, algae, or plant that is able to reproduce into a new plant without having to fuse with another reproductive cell.

Stamen — The male organ of the flower that consists of an anther and filament and produces pollen.

Stigma — The female reproductive part of the pistil, in the flower, that gets the pollen from whatever pollinates it.

Stolon — The technical term for a runner, or horizontal stem that grows on top of, or slightly below, the ground and produces new growth at buds and adventicious roots.

Stomate — A tiny pore on the outside of leaves, stems, and other organs that makes gas exchange possible.

Style — The long narrow stalk that connects the stigma to the ovary.

Systemic Pesticide — A pesticide containing chemicals that are absorbed into the plant and kill pests when they eat any part of the plant.


Thorns — Like a spine, but instead is a highly modified branch that ends in a sharp point. These occur where a branch would normally grow — in the axil of a leaf.

Tissue Culture — Under completely sterile conditions on a nutrient culture, a piece of a plant’s tissue, cell, or organ is used to grow entirely new plants that are clones.

Top Dress — Applying something to the top of a plant’s potting mix. Usually refers to adding more potting mix, fertilizer, or pebbles.

Transpiration — The act of a plant absorbing water through the roots and releasing it as a vapor through its stomates.

Trichomes —The little white fuzz you see on plants that can absorb water and nutrients from the air. A good example of a plant with trichomes is the air plant, or Tillandsia.

Tuber — A thick underground storage organ. For more information on tubers click here.


Umbel — An inflorescence that contains a group of short stalks with flowers that spread from the same point.


Variegated — Markings on a plant that are a different color.

Vermiculite — This is the shiny, brownish flake that you see in potting mixes that can sometimes feel spongy. For more information on potting mix additives click here.