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Hymenium
(of ascocarps, in section): the layer of tissue where
asci
arise and
spores
are
produced. Its thickness, colour, and the reactions, esp. with
J
, may be important in some
groups. The thickness should be measured starting from the roots of the
asci
, including the
epihymenium
. See also
thecium.
Hypha
(plural: hyphae): one of the filaments constituting the fungal
mycelium
.
Hypothallus
: marginal part of the
thallus
of
foliose
or
squamulose
lichens, composed only by
the fungus, normally with a different colour and texture
.
In these keys, this term is often
merged with
prothallus
.
Hypothecium
(of apothecia): in our keys this terms refers indiscriminately to all tissues located
below the
hymenium
. Its thickness, reactions and esp. pigmentation may be important for
identification. See also
subhymenium
.
Imbricate
(of thallus parts): overlapping, shingle-like, as the tiles of a roof, e.g. the squamules
of
Mycobilimbia lurida
.
Immersed
(of ascocarps and pycnidia): embedded in the substratum (e.g. the apothecia of
Clauzadea immersa
), or in the thallus (e.g. the perithecia of
Catapyrenium cinereum
).
Inflated
(of thallus parts): swollen.
Inspersed
(of the hymenium, in sections)
:
full of oil droplets which render it somehow milky,
not transparent in a microscopic section.
Involucrellum
(of perithecia): a usually black, lid-like structure originating from the upper part
of the
perithecium
, protecting the
ostiole
. It can be best observed - often under a binocular -
by vertically sectioning the perithecium. It is mostly limited to the upper part, but sometimes
it extends until the base of the perithecium. Its presence may be important for identification
(e.g. in
Catapyrenium s. lat.
,
Verrucaria
).
Isidia
(singular: isidium)
:
structures for the vegetative reproduction of the lichen, which derive
from swellings of the upper
cortex
, and contain
photobionts
. The true isidia are always
corticate
, as opposed to
soredia
. They may have different forms: erect and more or less
round in section (simple or ramified-
coralloid
), or flattened (
spatulate, peltate
), etc. See also
blastidia
,
phyllidia
, and
schizidia
.
Isidiate
(of thalli): with
isidia
.
Iso-
(general suffix): equal, e.g. isodiametric = more or less round in shape,
isotomic
.
Isotomic
(of thallus parts):
dividing in regular dichotomies into equal branches. See also
anisotomic
,
dichotomic, tetrachtomous
,
trichotomous
.
J
(reactions): the typical
Lugol
’s solution, which can be purchased by specialised furnishers: a
water solution with 1.5% of Iod and 10% of KOH solution.
K
(reactions): a ca. 10% water solution of potassium hydroxide (KOH). It can be substituted
with household lye (sodium hydroxide, NaOH).
KC
(reactions): the test is performed by wetting the tested area first with
K
, then with
C
. These
reactions are often ephemeral. In most cases, the
KC
test enhances the results obtained with
C
only.
Labriform
(of soralia):
soredia
originating from the lower face of lobes which tends to bent
upwards, the
soralia
assuming a lip-like form (e.g.
Hypogymnia physodes, Phaeophyscia
chloantha
).
Laciniae
(singular: lacinia): flattened parts of ramified
fruticose
lichens (e.g.
Ramalina
fraxinea
). Sometimes called
lobes
.
Laminal
: located on the upper surface of the thallus.
Lax
(of medulla): loose, not compact.
Lecanorine
(of apothecia): with a thalline
margin
containing
photobionts
. In most cases, the
colour of the margin is very different from that of the
disc
. In some genera, however the
colour is similar (e.g. in several species of
Caloplaca
), and one has to look for
photobionts
in microscopic sections. See also
aspicilioid
,
biatorine
,
lecideine
,
zeorine
.
