Dictreenary

General:

Allelopathy = the presence of biochemicals in plant tissues that interfere with the germination and growth of other plants

Buttress roots = rooting form in which the roots connect to the trunk for a substantial height up the bole of the tree. This form is most commonly observed in tropical, wetland species that require such structural support to maintain their stability in wet soil conditions

Cambium = a ring of living tissue between the bark (which is dead) and the wood (which is dead) in a tree. As this ring grows wider in circumference, the oldest cells on the edges of the ring die and become bark or wood, creating the growth rings seen on cut wood

Candle = the term for the vertical cluster of new growth needles that generally form on pines at the beginning of their growth season. Often these clusters will be covered in dense, woolly hairs

Dehiscent = describes a plant structure, usually a fruit, that breaks apart to release the seeds within

Epicormic shoot = a shoot which grows from a previously dormant bud located beneath the bark tissue and usually near the base of the tree

Fascicle = a tight bundle of flowers or leaves that grow from the same point on the plant. The term is most frequently used to describe the needle clusters found on Pines (Pinus spp.)

Glabrous = without hairs (leading to a smooth and glossy appearance)

Glaucous = having a greenish-blue appearance (as though a green surface is covered with a thin white-colored film)

Imbricate = overlapped in a sequential oder, as the petals of a rose or the leaves of an Eastern White Cedar

Internode = the space between two nodes of a stem/twig

Lenticel = an area of porous tissue in the bark that increases gas exchange between the inner tissue and atmosphere. Often appear as thin, horizontal ovals 0.5-2" long

Node = point of connection between the petiole and the twig/stem

Phloem = the tissues that transport sugar down from the leaves and throughout vascular plants

Pith = the soft, spongey tissue found at the center of twigs and stems of vascular plants. This tissue (also called the medulla) allows nutrients to flow through the plant

Revolute = rolled inward. Often used to describe leaves that have a downturned margin

Stomata = pore(s) in the surface of a leaf which opens and closes to regulate gas exchanges required for photosynthesis. Water leaves through stomata during transpiration

Tomentum = a layer of dense, woolly hairs

Vascular plants = plants that contain xylem and phloem tissue

Whorl = a group of plant structures all branching out from the same point on a central stem, creating a circular pattern like that of the spokes on an old wooden wheel

Xylem = the tissues that transport minerals and water up from the roots and around vascular plants

Leaves

Acicular = very slender or needle like in form

Abaxial = simply the upper side of any leaf or leaf-like structure on a plant. In more technical terms it is the side facing  toward the main vertical axis of a plant

Adaxial = the underside of any leaf or leaf-like structure on a plant (opposite of Abaxial)

Alternate leaf attachment = leaf attaches to the twig/stem one after the other

Bract = any modified leaf structure usually found growing at the base of a flowering or fruiting stem. A bract may also refer to the 'tassels' that develop between the scales of a cone on a conifer for example on the Douglas Fir and Oyamel.

Ciliate = hairs lining a plant structure, creating a similar appearance to the cilia along the cell membranes of single-celled organisms

Compound = describes a leaf that contains leaflets (not simple)

Doubly compound = describes a leaf comprised of leaflets which in turn have smaller leaflets known as pinnules

Entire = describes a leaf margin that is completely smooth (not serrated whatsoever)

Lamina = all the leaf tissue that is not part of the veins

Leaf base = the area where the stem of the leaf (petiole) connects to the leaf blade. Usually where the main vein(s) of the leaf originate

Leaf blade = sides of the leaf that have the greatest surface area

Leaf margin = the edge of the leaf blade

Leaflet = a division of a compounded leaf that is attached to the rachis

Lobe = a protrusion of the leaf blade between sinuses and away from the mid vein/center of the leaf

Opposite leaf attachment = leaf attaches to the twig/stem across from another leaf

Palmately compound = each leaflet connects at the same point on the petiole, radiating outward in a circular pattern. Examples include Horse Chestnut, Lupines and Virginia Creeper.

Petiole = stalk-like structure that attaches the leaf blade to the twig (not present on all leaves)

Pinnae = a general term for a single leaf-like structure that grows on a pinnate leaf

Pinnate = describes a pattern in the plant whereby structures (e.g. leaves, twigs, veins) occur opposite one another

Rachis = the central stalk-like structure of a compounded leaf which attaches the leaflets to the twig/stem. A rachis may also refer to the woody stick-like structure in the center of a cone to which the cone scales attach (see cone diagram below)

Serrate = describes a leaf margin that has teeth running along it, like a saw or a bread knife

Simple = describes a leaf that only has one petiole (not compound or doubly compound)

Sinus = an indentation of the leaf blade toward the mid vein/center of the leaf

Stipule = leaf-like structure that is often located at a node of the twig or at the base of the leaf petiole

Terminal leaflet = leaflet at the opposite end of the rachis from where it connects to the twig

Undulate = exhibiting a wavy appearance

Venation = used when describing the pattern that the veins make in a leaf e.g. parallel venation, alternate venation, pinnate venation

Fruit

Achene = small, dry fruit containing a single seed. The hard, dry fruit wall fits over the seed so closely that it seems like the seed coat, but is in fact a separate structure. The small yellow dots on the surface of strawberries are examples of achenes

Aril = seed covering that is typically fleshy or hairy and separate in form and structure from the pericarp

Bract = the term for one of the 'tassels' that develop between the scales of a cone on a conifer for example on the Douglas Fir and Oyamel. A bract may also refer to any modified leaf structure, but they are usually found at the base of a flowering or fruiting stem

Cupule = a cup shaped structure of interlocking bracts such as those around acorns or hazelnuts

Drupe = fruiting structure in which a single seed is enclosed by fleshy, soft tissue. Examples of drupes are peaches, mangoes, walnuts, almonds and olives

Endocarp = the center of a fruit where seeds are sometimes located. Examples include an apple core, a peach stone and the entire edible part of a banana

Exocarp = the outer most layer of a fruit, commonly referred to as a skin, husk or peel

Hilum = a scar formed on the area where the seed was previously attached to the ovary (like a belly-button for seeds)

Infructescence = a tight cluster of fruits on the same stem. May also be defined as the fruiting stage of an inflorescence

Mesocarp = the fleshy tissue immediately within the endocarp such as the main edible parts of an apple, peach or cherry

Pappus = an arangment of long, fine fairs attached to the seed which often give a feathery, cotton-like appearance and make the seed more aerodynamic. The cottony fluff on a Cottonwood seed and the hairs creating the parachute-like structure on a Dandelion seed are examples.

Pericarp = the fleshy part of a fruit. Sometimes nutritionally rich and colorful to encourage consumption by animals as in apples, grapes and tomatoes

Rachis = the woody stick-like structure in the center of a cone to which the cone scales attach (see cone diagram below). Rachis may also refer to the central stalk-like structure of a compounded leaf which attaches the leaflets to the twig/stem

Samara = a type of fruit design characterized by two fused seeds each flaring out into a predominant wing structure. Commonly known as 'helicopters' and very typical of Maple species (Acer spp.) 

Umbo = the tip of a scale on a cone. When the scales are appressed as in unopened cones, only the umbo is visible. See cone diagram below

Flowers

Catkin = a hanging, spike-like cluster of flowers or fruits. See 'Types of Flower Inflorescence' below

Dioecious = describes a species in which each individual either produces female or male flowers

Fabaceous flowers = flowers seen on members of the Fabaceae family. Such flowers are characterized by their unique shape of banner above, keel at the base and two wings either side of the keel

Banner = a large petal that curves upward from the center of the flower and faces away from the central stem of the plant

Keel = a set of folded petals beneath the flower's center, forming a tube structure similar in appearance to the keel of a ship

Wings = petals attached to either side of the keel, sometimes enclosing it,  at other times spreading away

Imperfect flower = a flower that contains either only male reproductive organs or only female reproductive organs

Monoecious = describes a species in which an individual may have both female and male reproductive organs. A tree with either perfect flowers or imperfect flowers from each sex is considered monoecious

Panicle = a flowering structure in which pedicels attach to auxiliary peduncles which are in turn connected to the central, vertical peduncle. The two-layers of attachment is similar to doubly compound leaves.

Pedicel = the stalk that attaches directly to the flower head. The other end either connects the flower to the branch or a peduncle

Peduncle = stem-like tissue to which multiple pedicels attach in a compound flower structure

Perfect flower = a flower that contains both male and female reproductive organs

Pistil = the set of organs that provide all the female reproductive functions for the flower (includes the ovaries, style and stigma)

Stamen = the set of organs that provide all the male reproductive functions for the flower (includes the filament and anther)