| Bryophytes | Terrestrial plants that lack a vascular system, are dependent on environmental moisture for reproductive and nutritive functions, and that disperse spores for reproduction. The group includes mosses, liverworts and hornworts. |
| Tracheophytes | Plants with a vascular system that helps them to stay upright and transports the sap, the plants' nutritive liquid mixture. The vascular system is made up of the vascular tissues xylem and phloem. The group includes pteridophytes and flowering plants. |
| Pteridophytes | Terrestrial plants with a vascular system that are dependent on environmental moisture for reproductive and nutritive functions and that disperse spores for reproduction. The group includes ferns and horsetails. |
| Flowering plants | Or seed plants. Plants with a vascular system that are not dependent on environmental moisture for reproductive and nutritive functions and that disperse seeds produced inside flowers for reproduction. The group includes gymnosperms and angiosperms. |
| Gymnosperms | Vascular flowering plants in which the ovules are not protected by an ovary. As they don't have ovaries, they don't have fruits neither, but cones instead. Their flowers are not very conspicuous, as they lack petals and sepals. They are woody and most of them belong in the conifers (such as the pines, cedar-trees, fir-trees, spruces and cypresses). |
| Angiosperms | A vascular flowering plant in which the ovules are enclosed inside protective ovaries and the seeds inside fruits. They use to have well-visible flowers that, when complete, are made up of sepals, petals, stamens and pistils. They can be herbaceous (like the poppy) or woody (like the oak). |
| Leaf | It is the photosynthesis and transpiration organ in plants. Its two main parts are usually the petiole (a slender stem that supports the blade) and the blade (the green and usually flat area, with a midrib and secondary veins). When they have one only blade, they are called "simple leaves", whereas if they have several leaflets (each one resembling a single leaf with its petiole and its blade) they are called "compound leaves". You can tell whether something is a leaf or just a leaflet by watching the stipules: two membranes that are always at the base of the leaf, and never in the base of a leaflet. Holm-oaks have simple leaves, while ash-trees have compound leaves. |
| Palmate | Compound leaves can be palmate, resembling a hand, with the leaflets outspread. |
| Pinnate | Compound leaves can be pinnate, resembling a feather, with the leaflets arranged on both sides of a central axis. |
| Whorl | Two or more leaves or other structures surrounding a stem at the same point. |
| Bract | A leaf associated with the flowers or inflorescences of a plant. Bracts are usually different in appearance to the other leaves on the plant. The lime-tree has very conspicuous elongated, narrow and pale-green bracts. |
| Involucre | A whorl of bracts, often cup-like, at the base of a flower, an inflorescence or a fruit. Daisies have involucres at the base of their inflorescences, and oaks have involucres at the base of the acorns. |
| Deciduous | To fall off or shed seasonally; usually refers to the leaves of a plant. It's opposite to evergreen. A poplar has deciduous leaves, while a holm-oak is evergreen. |