The terms used on this site, defined.

Plain-English definitions of the botanical and care terms used throughout our guides. Click any term in an article to jump back here.

Aerial root

A root that grows above the soil line, often used by climbing aroids like monstera and philodendron to attach to surfaces and absorb moisture from the air.

Axil

The angle between the upper side of a leaf or branch and the stem it attaches to. New growth (buds, side shoots, aerial roots) typically emerges from the axil.

Bottom watering

Setting a pot in a tray of water and letting the soil draw moisture up through the drainage holes. Ideal for plants that resent water on the leaves (African violet) or for evenly rehydrating bone-dry soil.

Calcium oxalate

Sharp microscopic crystals found in many aroids (pothos, monstera, philodendron) that cause oral irritation and swelling when chewed by cats, dogs, or humans. The reason ASPCA classifies these plants as toxic.Source: NIH MedlinePlus

Cultivar

A cultivated variety of a plant species, bred or selected for specific traits like variegation, leaf shape, or compact growth. Written in single quotes after the species name (e.g., Monstera deliciosa ‘Thai Constellation’).

Epiphyte

A plant that naturally grows on another plant (usually a tree) rather than in soil, absorbing water and nutrients from rain, air, and debris. Air plants, many orchids, and some philodendrons are epiphytes.

Fenestration

The natural holes or splits that develop in the leaves of mature monstera and some philodendrons. Caused by uneven leaf growth and thought to help the plant tolerate wind and reach more light in the canopy.

Leaf node

The point on a stem where a leaf, bud, or aerial root attaches. Propagation cuttings must include at least one node to root — the node is where new roots emerge.

LECA

Lightweight Expanded Clay Aggregate — small fired-clay balls used as a substrate for semi-hydroponic plant care. Inert, reusable, and drains freely. Popular for aroids and as a top-dress layer.

Perlite

A naturally-occurring volcanic glass expanded by heat into white, lightweight, porous pellets. Added to potting mix to improve drainage and aeration without adding nutrients.

Petiole

The stalk that connects a leaf to the main stem of the plant. Petiole length and stiffness are diagnostic traits between similar species (e.g., philodendron vs. pothos).

Photoperiod

The total hours of light a plant receives in 24 hours. Short-day plants (poinsettia, Christmas cactus) need long uninterrupted dark periods to bloom; long-day plants need 14+ hours of light.

Propagation

Producing new plants from cuttings, division, seed, or other methods. Stem cuttings (with at least one node) are the most common method for indoor aroids and tropicals.

Rootbound

When a plant’s roots have grown so densely they circle the pot wall and fill the container, leaving little soil for water retention. Signs: roots out the drainage holes, fast drying, slowed growth.

Stomata

Microscopic pores on leaf surfaces (mostly underside) through which the plant exchanges water vapor, CO₂, and oxygen. Dust on leaves clogs stomata and reduces photosynthesis.

Variegation

Patches of cream, white, yellow, or pink on otherwise-green leaves caused by lack of chlorophyll in those areas. Variegated plants need brighter light because the white sections don’t photosynthesize.