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Hilum: The scar on a seed that marks the point at which it was attached to the plant.* Bean seeds have very obvious hilums. From left to right in the picture: …

Velamen: The thick sponge-like covering of the roots of epiphytic orchids which helps prevent water loss and aids in absorption.*   *Allikas, G. & Nash, N. (2000). Orchids. London: PRC.

Zygomorphic: Bilaterally symmetrical, so that a line drawn through the middle of the structure along only one plane will produce a mirror image on either side.* Orchid flowers are zygomorphic. …

Lenticel: A pore in the stem of a woody plant, showing as a raised spot that may be filled with a powdery substance. The pore permits air to reach tissues below …

Marcescent (mar-ses-ent): of parts of certain plants, remaining attached to the plant when withered.* Many oak (Quercus spp.) and beech (Fagus spp.) trees have marcescent leaves that persist well into the …

Pectinate: Arranged like the teeth of a comb; usually two-sided with respect to leaves.* Fir trees (Abies sp.) often show pectinate arrangement of their needles. *Eckenwalder, J.E. (2009). Conifers of the …

Equitant: Of leaves, overlapping or straddling in two ranks, as the leaves of Iris.* This Phormium (New Zealand Flax plant) in the library shows equitant leaf growth. *Harris, J.G., Harris, M.W. …

Bract: A leaflike organ subtending an inflorescence. Bracts are sometimes brightly coloured and petal-like, as in poinsettia (Eurphorbia pulcherrima)* Poinsettias are grown for their bright red bracts which surround their small …

Acerose: Needle-shaped, as the leaves of pine or spruce.*   *Harris, J.G., Harris, M.W. (2001). Plant identification terminology: An illustrated glossary (2nd ed.). Spring Lake: Spring Lake Publishing.