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