Major.   Greater in size

Malacophily.   Pollinated by snails or slugs

Male or Staminate.   Plant with staminate flowers only

Marbled.   A surface traversed by irregular veins of color; as block of marble often is

Marcescent.   Usually ephemeral with persistent remains; withering persistent

Marginal.   Pertaining to the border or edge

Massula.   A clump of microspores, as in Azolla

Matutinal.   With flowers opening in the morning

Medial.   Upon or along the longitudinal axis

Median.   With stipules adnate to petiole with free part of stipules near middle of petiole

Median Leaf.   Leaf on top of stem, as in heterophyllous species of Selaginella

Megasporangium.   The sporangium in which megaspores are produced

Megaspore.   A spore that gives rise to a female gametophyte

Megasporophyll.   Modified leaf bearing ovules; e.g., Zamia

Melittophily.   Pollinated by bees

Membranous.   Thin and semi-translucent; membrane-like

Meniscoidal.   Thin and concaveconvex

Mericarp.   A portion of fruit that seemingly matured as a separate fruit

Mermaphrodigynous.   Inflorescence with hermaphroditic flowers inside or above and pistillate outside or below (hermaphrodigynecephalous)

Mesocarp.   Middle layer of pericarp

Metaphyll.   Adult leaf

Micro.   Axial embryo in minute seeds, less than 0.2 mm long; minute and undifferentiated to almost total size of seed

Micromelittophily.   Pollinated by small bees

Micropyle.   Hole through integument(s)

Microsporangium.   The sporangium in which microspores are produced

Microspore.   A spore that gives rise to a male gametophyte

Microsporophyll.   Modified leaf bearing microsporangia or pollen sacs

Midrib.   The central conducting and supporting structure of the blade of a simple leaf

Midvein.   The central conducting and supporting structure of the blade of a leaflet

Minor.   Smaller in size

Minute.   Very small

Mixed.   Contains flower, leaf, and stem primordia; will give rise to branch with leaves and flower(s)

Monad.   Pollen grains occurring singly

Monadelphous.   With one group of stamens connate by their filaments

Moniliform.   Elongate roots with regularly arranged swollen areas

Monocarpellate.   One-carpelled

Monocarpic, Hapaxanthic.   Perennial or annual, flowering and fruiting once, then dying; fruiting once

Monocephalous.   One-headed, as in composites

Monochasium.   A cymose inflorescence with one main axis

Monocotyledonous.   With one cotyledon

Monocyclic.   One-whorled

Monoecious.   With staminate and carpellate flowers on same plant

Monoecious.   Plant with all flowers imperfect, but staminate and pistillate flowers on same plant

Monolete Spore.   Bean-shaped, with a single scar line

Monomerous.   Whorl with one member

Monomorphic.   All of the same shape and size

Monophyllous.   One-leaved

Monopodial.   Branching with a main axis and reduced or missing laterals; excurrent

Mucilaginous.   Gummy or gelatinous

Mucronate.   Less than 3:1 l/w, straight and stiff

Mucronulate.   1:1 l/w or broader than long; straight

Multicellular.   Many-celled

Multicipital.   With many axes or stems from one rootstock or caudex

Multicostal.   Many-ribbed

Multilocular.   Many-locular

Multinodal Shoot.   Spring shoot developing from the terminal winter bud and producing 2 or more whorls of branches; the cones are partly lateral in the middle of the shoot; e.g., Pinus echinata

Multiseriate.   Many-rowed; in many series

Multistriate.   Many-lined

Muricate.   Covered with short, hard protuberances

Muriculate.   Minutely muricate

Muticous.   Without a vein extension, awn or hair

Myiophily.   Pollinated by diptera

Myrmecophily.   Pollinated by ants

Nanophyllous.   With leaves to 225 sq. mm in size.

Napiform.   Turnip-shaped

Navicular.   Boat-shaped

Neck.   Narrowed portion of hypanthium, between the base and a flared limb

Necrocoleopterophily.   Pollinated by carrion beetles

Nectar Secreting Glands.   Sugary compound producing glands found mostly on floral parts that produce attractants for pollinators

Nectary.   A specialized nectar-secreting structure or area

Needle.   Acicular; slender, elongated leaf, usually over 2 in long; e.g., Pinus

Net.   Veins uniting to form a network

Neuter or Agamous.   Without stamens and carpels in flower; or sex organs abortive

Nocturnal.   Opening during night

Nodal.   At the nodes

Node.   Point on the stem where leaves are attached; or the point of branching of the stem

Nodiform or Nodulose.   Knotty or knobby, as the roots of most of the Fabaceae

Nucellus.   Female sporangium within ovule; megasporangium in seed plants

Nut.   A one-seeded, dry, indehiscent fruit with a hard pericarp, usually derived from a one-loculed ovary

Nutlet.   A small nut

Obconic.   Inversely conical

Obcordiform.   Inversely cordiform

Obdiplostemonous.   With stamens in two whorls, outer opposite petals, inner opposite the sepals

Oblique.   Having an asymmetrical base

Oblong.   With widest axis at midpoint of structure and with margins essentially parallel

Obovate.   Inversely ovate

Obscure.   Not clearly visible macroscopically, usually owing to incomplete differentiation

Obtriangular.   Inversely triangular

Obtrullate.   Inversely trullate

Obtuse.   Margins straight to convex, forming a terminal angle more than 90

Ocellated.   A broad spot of some color has another spot of a different color within it

Ocreate.   Having a stipular tube surrounding stem above insertion of petiole or blade

Ocreolate.   Diminutive of ocreate; usually applied to bract bases

Oligomerous.   With reduction in number of members within whorl

Oligotaxy.   Reduction in number of whorls

Opaque.   With a dull surface

Operculate Capsule.   One that dehisces through pores, each of which is covered by a flap, cap, or lid, as in Papaver

Opposite.   Two leaves or other structures per node, on opposite sides of stem or central axis

Ornithophily.   Pollinated by birds

Orthotropous or Atropous.   With straight body so that funicular attachment is at one end and micropyle at other

Osseous.   Bony

Ovary.   Ovule-bearing part of pistil

Ovate.   With widest axis below middle and with margins symmetrically curved; egg-shaped

Ovulate.   Female; bearing ovules only in the flowers

Ovule.   Embryonic seed consisting of integument(s) and nucellus

Ovuliferous Scale.   Highly modified lateral branch in the axil of a leaf (bract), and bearing ovules; may be flat or peltate, woody or fleshy; e.g., Pinaceae