An ascocarp in which the hymenium is exposed at maturity. Generally cup- or
saucer-shaped, apothecia can also be long and narrow (lirellae).
AREOLATE
Having division by cracks into small areas. Descriptive of a thallus marked
off into minute, usually polygonal areas (areoles) like a jigsaw pattern with
pieces together or somewhat separated.
ASCOCARP (=ASCOMA)
An ascus-containing fruiting body. Apothecia and perithecia are the most common
types of ascocarps associated with lichens.
ASCOSPORES
A spore produced in an ascus. Ascospores are sexual spores. Often diagnostic,
in addition to the number of ascospores per ascus, are their shape, size, color,
and number of cells.
ASCUS
The sac-like structure in which ascospores are found. They vary in shape from
narrow and elongate to nearly round. While the number of ascospores per ascus
in usually 8, 1, 2, 4, 6, as well as numerous ascospores per ascus are also
known.
ASEXUAL REPRODUCTION
Asexual or vegetative reproduction in lichens may be by 1) simple fragmentation
of the thallus, 2) the development of soralia which contain minute powdery propagules
(soredia), and 3) the development of numerous small, simple or branched-coralloid,
corticate isidia. These methods involve the dissemination of the united mycobiont
and photobiont. The position, shape, texture, and color of the soralia and isidia
are often diagnostic. A number of species also develop immersed, flask-shaped
pycnidia in which numerous, often charateristically-shaped conidia develop.
(Conidia are asexual spores)
CEPHALODIA
Minute growths occurring on or within the thallus of many lichens, cephalodia
are, in reality, very tiny lichen thalli containing a blue-green alga different
from the alga of the host lichen. They vary in size from tiny warty lobules
to large fruticose structures. They are known in about 400 lichen species in
diverse groups.
CILIA
Hair-like (hyphal) thalline appendages, occurring at the thallus or apothecial
margin.
COLLECTION DATA THAT NEEDS TO BE RECORDED
--Pinpoint the exact location of the are being collected (Can someone unfamiliar
with the area find the same spot 100 years later?)
--Describe the substrate or name it accurately.
--State the general habitat, e.g., roadside, old field, north-facing slope.
--Record the county, including township and range, and state.
--Always include the collector's name and the date of the collection.
CORTEX
The outer hyphal surface layers of the lichen thallus. The term applies to
both the upper and lower surfaces: Upper cortex, lower cortex.
CYPHELLAE
A break in the lower (rarely upper) cortex of a lichen thallus which is roundish
or ovate and in section appears cup-like. Exposes medullary hyphae. Characteristics
of Sticta.
HOLDFAST
An algal-free thickeded mass of hyphae used for attachment. For example, the
organ of attachment of Usnea, old man's beard.
HYMENIUM
The spore-bearing layer of a fruiting body, hte hymenium is composed of the
asci (containing the ascospores) intermixed with the sterile hyphae called paraphyses.
HYPHAE
The strands or filaments of the mycelium of a fungus, hyphae are the segmented
cells that constitute the body of the mycobiont of a lichen.
HYPOTHALLUS (=PROTHALLUS)
An algal-free white or dark brown to black zone (containing only the mycobiont)
sometimes visible between areolae and at the growing margins of crustose lichen
thalli. They hypothallus is the first hyphae of the thallus to grow. Hypothallus
also describes the spongy (hyphal) tissue on the underside of the thallus of
genera like Anzia.
ISIDIA
Small, cylindrical, coralloid or flattened, simple or branched outgrowths
from the surface of the thallus. As extrusions of cortical, algal, and medullary
tissues, they serve as asexual (or vegetative) reproductive bodies.
LECANORINE APOTHECIA
Apothecia with a thalline margin, i.e., with a border or rim around the central
disc that is the same color as the parent thallus. Such a margin is also characterized
by containing algal cells.
LECIDEINE APOTHECIA
Apothecia without a thalline margin. If a border or rim is evident around
the central disc, it is called a proper margin and will be the color of the
disc and not the color of the parent thallus. The margins of such apothecia
are without algae.
LICHENS
The lichens are a biological and not a systematic group and each is basically
a stable self- supporting association of a fungus (the mycobiont) and an alga
(the photobiont). They are unique in that in many (but not all) cases the resulting
life form and behavior differ markedly from that of the isolated components.
LIRELLAE
A long, narrow apothecium.
MEDULLA
The loose layer of hyphae below the upper cortex and algal layer.
MYCOBIONT
The fungal component of a lichen, the mycobionts of most lichens (98%) belong
to the fungal Subdivision Ascomycotina (the "sac fungi"). Lichenization also
occurs in a few members of the fungal Subdivisions Basidiomycotina (the "club
fungi") and Deuteromycotina, as well as the enigmatic Geosiphon. Names given
to lichens are considered as referring to the mycobiont.
PERITHECIA
An Ascocarp in which the hymenium is enclosed at maturity - lining the bottom
of the perithecium on the inside. Perithecia are imbedded to sometimes on the
surface of lobes. Compare Pycnidia.
PHOTOBIONT
The photosynthetic symbiont of a lichen which may be a green alga (phycobiont),
or a blue-green alga (cyanbiont). Some 37 genera have now been identified as
lichen photobionts.
PRUINA (PRUINOSE)
A powdery or frosty bloom on the surface of the thallus or fruiting body.
PSEUDOCYPHELLAE
Tiny, undifferentiated openings (often appearing as small nicks) in the upper
or lower cortex through which medullary hyphae often protrudes. They provide
valuable taxonomic characters.
PYCNIDIA
Small, flask-shaped structures that are filled with simple or branched hyphae
from which bud numerous asexual spores (conidia). They may be confused with
perithecia (which contain the sexual ascospores) since they both are immersed
in the medulla and open through a pore in the cortex. This pore (or ostiole)
appears as a brown to black dot in the upper cortex of the thallus.
RHIZINES
Black to light brown cords of hyphae extending from the lower cortex to the
substrate and anchoring the thallus firmly.
THALLUS
The vegetative body of a lichen.
THALLUS CLADONIAEFORM
A form of fruticose lichens in which upright podetia rise above a crustose
or squamulous primary thallus. Podetia are simple and unbranched, sparingly
branched, or richly blanched and shrublike.
Thallus crust-like and wholly or partially developing within the substrate.
At times appearing as just a colored stain. If superficial, then appressed and
tightly attached, with rhizines absent or minute.
Thallus "leaf-like", with lobes distinctly formed. Lobes usually broadened
and contiguous, independent of each other to crowded and overlapping. Adnate
to loosely attached to the substrate by rhizines.
Thallus shrub-like or beard-like, fruticose lichens may be erect or pendulous.
The branches are cylindrical or strap-shaped and they are often richly branched.
They have a radial structure and are attached to the substrate at a single,
usually basal, point or are unattached.
THALLUS LEPROSE
Thallus lacking internal organization into cortex, medulla, or algal layers;
entirely dissolved into soredia.
THALLUS STRATIFIED (=HETEROMEROUS)
Descriptive of the internal structure of the thallus, a stratified lichen
is one in which the photobiont (the alga) is in a compact layer below the upper
cortex. Most lichens have a stratified thallus and include crustose, foliose
and fruticose growth forms.
THALLUS SQUAMULOSE
A form intermediate between foliose and crustose thalli, a squamulose thallus
is one with small, usually overlapping, flattened lobes or scales.
THALLUS UMBILICATE
A form of foliose lichens that is roughly circular in outline and attached
to the substrate by a single set of coalescent hyphae. Characteristic of the
so-called "rock tripes" in the family Umbilicariaceae.
THALLUS UNSTRATIFIED (=HOMOIOMEROUS)
Descriptive of the internal structure of the thallus, an unstratified lichen
is one in which the photobiont (always a blue-green alga) is distributed at
random throughout the thallus. Such thalli include crustose, foliose and fruticose
growth forms. The term unstratified refers specifically to the internal structure
of the gelatinous lichens.
THE GELATINOUS LICHENS
Descriptive of those lichens with an unstratified thallus, the gelatinous
lichens are usually dark bluish, slate-colored to black. The dark color is the
result of the fact that blue-green algae are intermixed throughout the thallus.
In addition to the dark color of the thallus, the gelatinous lichens can also
be recognized by the fact that they tend to take on the consistency of moist
gelatin when wet.
TOMENTUM (TOMENTOSE)
A mat of short fungal hyphae having a downy or woolly appearance.
SEXUAL REPRODUCTION
Only the mycobiont reproduces sexually, a process culminating in the development
of an ascocarp containing ascopores.
SORALIUM
Decorticate portions of a lichen thallus where soredia are located. Usually
formed from medullary hyphae thrusting upwards through cracks or pores in the
upper cortex. Soralia may be diffuse (the upper surface of the lichen becoming
a continuous soredial mass) or delimited (i.e., confined to well-defined areas).
Soralia may be laminal (on the surface) or marginal in position and their texture
may be farinose (fine or meal-like) or granular.
SOREDIA
Non-corticate combination of photobiont and fungal hyphae having the appearance
of powdery granules. Soredia are capable of reproducing a lichen vegetatively.
They are generally produced in localized masses called soralia.
SUBSTRATE
The material on which the lichen is growing or to which it is attached. Lichens
may be:
