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B & T World Seeds
Common Name:
Botanical name:
Glossary P - R
pachycaul:
thick-stemmed, not `twiggy' (unbranched, or the branches few and thick).
palea:
in a grass
floret
, the upper one of the two
bracts
enclosing a
flower
.
palmate:
of a leaf,
divided
into several
leaflet
s which arise at the same point.
palmatifid:
of a leaf, deeply
divided
into several
lobes
which arise (almost) at the same level. cf.
pinnatifid
.
palmatisect:
a condition intermediate between
palmate
and palmatifid, with the green tissue of the
lamina
completely
divided
into several
segment
s, but the
segment
s not fully separated at the base.
palynology:
the scientific study of
pollen
.
panicle:
a
compound
raceme
; an
indeterminate
inflorescence
in which the flowers are borne on branches of the main
axis
or on further branches of these.
paniculate:
indeterminate
and much branched.
pantoporate:
of a
pollen
grain, with rounded apertures all over the surface.
papilla:
a small, elongated protuberance on the surface of an organ, usually an extension of one epidermal
cell
. adj. papillose.
pappus:
a tuft (or ring) of hairs or
scale
s borne above the
ovary
and outside the
corolla
in asteraceae and possibly representing the
calyx
; a tuft of hairs on a
fruit
.
parasite:
an organism living on or in a different organism and deriving nourishment from it. cf.
saprophyte
,
epiphyte
.
paratype:
a specimen, other than the
holotype
, that was cited with the original publication of a name.
parenchyma:
plant tissue consisting of mature, living
cell
s that are relatively unspecialised in function.
parietal:
attached to the margins of a structure; of
placentation
, having the
ovule
s attached to
placenta
s on the wall of the
ovary
.
paripinnate:
having an even number of
pinnae
by virtue of having a pair in the
terminal
position. cf.
imparipinnate
.
parted:
divided
, almost to the base, into
segment
s.cf.
palmate
,
lobed
pedate:
of a
palmate
or palmately-
lobed
leaf, having the lateral
segment
s
divided
again.
pedicel:
the stalk of a
flower
. adj. pedicellate.
peduncle:
the stalk of an
inflorescence
; in ferns, the stalk of a
sporocarp
. adj. pedunculate.
pellucid:
transparent.
peltate:
of a leaf, having the stalk attached to the lower surface of the
blade
, not to the margin (also applied, in the same sense, to other stalked structures).
pendulous:
drooping; of
ovule
s, attached at the top of the
ovary
and hanging downwards from an
apical
placenta
.
penicillate:
pencil-shaped; tufted like an artist's brush.
penninerved (= penniveined):
having conspicuous lateral
vein
s divergent from the
midrib
and lying approximately parallel to each other.
penniveined:
with conspicuous lateral
vein
s diverging from the
midrib
and lying approximately parallel to each other.
pentamerous:
of a
flower
, having five parts in each
floral
whorl
(not necessarily including the
gynoecium
).
pepo:
literally, a pumpkin (latin); a
fruit
with firm skin, pulpy interior, many
seed
s and a single locule.
perennate:
maintain a dormant, vegetative state throughout non-growing seasons.
perennial:
a plant whose life span extends over more than two growing seasons.
perfoliate:
of a
sessile
leaf or
bract
, having its base completely wrapped around the
stem
.
perianth:
the
calyx
and
corolla
of a
flower
, especially where the two are similar.
pericarp:
the wall of a
fruit
, developed from the
ovary
wall.
perigynous:
of perianth
segment
s and
stamen
s, arising from a cup or tube (
hypanthium
) that is free from the
ovary
but extending above its base. cf.
hypogynous
,
epigynous
.
perisperm:
nutritive tissue in an
angiosperm
seed
, formed from the
nucellus
. cf.
endosperm
.
persistent:
remaining attached to the plant beyond the expected time of falling (e.g. of
sepals
not falling after flowering).
petal:
a member of the inner
whorl
of non-fertile parts surrounding the fertile organs of a
flower
, usually soft and coloured conspicuously.
petaloid:
like a petal; soft in texture and coloured conspicuously.
petiole:
the stalk portion of a leaf.
petiolule:
the stalk portion of a
leaflet
.
phanerogam:
(literally) a plant with conspicuous reproductive parts; a plant reproducing by
seed
s. cf.
cryptogam
.
phenotype:
the physical characteristics of an organism; the outward expression of characteristics conferred on an organism by its
genotype
.
phloem:
the tissue in the conducting system of a plant through which metabolites (products of chemical reactions in the plant) are transported.
phyllichnium:
in casuarinaceae, the ridge of a branchlet
aristate
; pl. phyllichnia.
phylloclade:
a very leaf-like, photosynthetic
stem
of a plant whose true leaves are much reduced. cf.
cladophyll
.
phyllode:
a leaf whose
blade
is much reduced or absent, and whose
petiole
and
rachis
have assumed the functions of the whole leaf. cf.
cladode
.
phyllotaxy:
the arrangement of leaves on a
stem
(when spiral, often expressed quantitatively as the fraction of the circumference of the
stem
that separates two successive leaves).
phylogeny:
the evolutionary development of a plant group, i.e. its derivation from its ancestors and the relationship among its members. adj. phylogenetic.
phylum:
a
taxon
of high rank, the major unit of classification. cf.
division
.
pilose:
hairy, the hairs soft and clearly separated but not sparse.
pinna:
a primary
segment
of the
blade
of a
compound
leaf.
pinnate:
divided
into pinnae; once-
compound
. cf.
bipinnate
,
tripinnate
.
pinnatifid:
cut
deeply into
lobes
that are spaced out along the
axis
(of the leaf). cf.
palmatifid
.
pinnatisect:
dissected down to the
midrib
but having the
segment
s confluent with it.
pinnule:
a
leaflet
of a
bipinnate
leaf.
pistil:
a free
carpel
or a group of fused
carpel
s.
pistillode:
a sterile pistil, often
rudimentary
.
pith:
the central region of a
stem
, inside the
vascular
cylinder.
placenta:
a region, within an
ovary
, to which
ovule
s are attached.
placentation:
the arrangement of placentas, and hence of
ovule
s, within an
ovary
.
plicate:
folded back and forth longitudinally like a fan.
plumose:
like a feather; with fine hairs branching from a central
axis
.
plumule:
the portion of an
embryo
that gives rise to the shoot system (as distinct from the
root
system) of a plant. cf.
radicle
.
pneumatophore:
an air-
vessel
; an organ containing
aerenchyma
; in particular, a root of a mangrove plant, growing above the substratum.
pod:
a
leguminous
fruit
.
pollen:
the
microspore
s of
seed
plants; the powdery mass of microspores shed from
anthers
.
pollen-grain:
see
grain
.
pollen-sac:
see
sac
.
pollination:
the transfer of pollen from the male organ, where it is formed, to the receptive region of a female organ, e.g. from
anther
to
stigma
.
pollinium:
a cohering mass of pollen grains, transferred as a unit in
pollination
. pl. pollinia.
polygamodioecious
: having
bisexual
and male flowers on some plants, and
bisexual
and female flowers on others.
polygamous:
having
bisexual
and
unisexual
flowers on the same plant.
polymorphic:
having more than two distinct morphological variants.
polypetalous:
with free petals. cf.
gamopetalous
.
polyphyletic:
composed of members that originated, independently, from more than one evolutionary line. cf.
monophyletic
.
polyploid:
having more than two of the basic sets of
chromosome
s in the
nucleus
. cf.
diploid
,
haploid
polytypic:
containing more than one
taxon
of the next lower rank. cf.
monotypic
.
pome:
a fleshy (false) fruit, formed from an
inferior
ovary
, in which the
receptacle
or
hypanthium
has enlarged to enclose the true
fruit
.
porate:
of a pollen grain, with rounded apertures only. cf.
colporate
.
posterior:
of
floral
parts, on the side of the
flower
nearest to the
axis
. cf.
anterior
.
praemorse:
appearing bitten off at the end.
prickle:
a hard, pointed outgrowth from the surface of a plant, involving several layers of
cell
s but not containing a
vein
.
probract:
small, leaf-like structure at the base of an
inflorescence
in cucurbitaceae, usually arising opposite a
tendril
.
procumbent:
trailing or spreading along the ground but not rooting at the
node
s. cf.
adventitious
,
runner
,
stolon
.
proliferous:
in conostylis, having erect or spreading, elongating
stem
s which are capable of rooting at the
node
s but rarely do so.
propagule:
a structure with the capacity to give rise to a new plant, e.g. a
seed
, a
spore
, part of the vegetative body capable of independent growth if detached from the parent.
prophyll:
a leaf formed at the base of a shoot, usually smaller than those formed subsequently.
prostrate:
lying flat on the ground.
protandrous:
having the male sex organs maturing before the female; of a
flower
, shedding the
pollen
before the
stigma
is receptive. cf. protogynous.
prothallus:
a
gametophyte
body, especially in ferns and related plants.
protogynous:
having the female sex organs maturing before the male; of a
flower
, shedding the
pollen
after the
stigma
has ceased to be receptive. cf.
protandrous
.
proximal:
near to the point of origin or attachment. cf.
distal
.
pruinose:
having a whitish, waxy, powdery bloom on the surface.
pseudo-:
false; apparent but not genuine.
puberulous:
covered with minute, soft, erect hairs.
pubescent:
covered with short, soft, erect hairs.
pulvinus:
a swelling at the base of the stalk of a leaf or
leaflet
, often
glandular
or responsive to touch.
punctate:
marked with dots.
puncticulate:
minutely dotted.
pungent:
ending in a stiff, sharp point; having an acrid taste or smell.
pustulate:
covered with small pustule- or blister-like elevations.
pyrene:
the 'stone' (
endocarp
plus
seed
) of a succulent
fruit
. cf.
berry
,
drupe
.
quincuncial:
of the arrangement of
corolla
lobes
in a bud, a variant of
imbricate
aestivation
.
raceme:
an
indeterminate
inflorescence
in which a main
axis
produces a series of
flowers
on lateral stalks, the oldest at the base and the youngest at the top. adj. racemose.
rachilla:
the
axis
of a grass
spikelet
, above the
glumes
.
rachis:
the
axis
of an
inflorescence
or a
pinnate
leaf; pl. rachises.
radical:
of leaves, clustered at the base of the
stem
.
radicle:
the portion of an
embryo
that gives rise to the
root
system of a plant. cf.
plumule
.
raphe:
the part of the stalk of an
anatropous
ovule
that is fused along the side of the
ovule
.
raphides:
needle-like crystals that occur in bundles in the vacuoles of some plant
cell
s.
ray:
a
zygomorphic
flower
in asteraceae; a radial band of
cell
s traversing the conducting elements in woody
stem
s.
ray:
of a
compound
umbel
, one of the first (lower) series of branches of the
inflorescence
axis
.
receptacle:
the
axis
of a
flower
(=
torus
); in ferns, an axis on which sporangia arise.
recurved:
curved or curled downwards or backwards.
reflexed:
bent sharply downwards or backwards.
regular:
see
actinomorphic
.
reniform:
kidney-shaped.
replum:
a longitudinal partition in an
ovary
, formed between
parietal
placenta
s.
resupinate:
twisted through 180°, e.g. as with the
ovary
of most orchidaceae.
reticulate:
forming a network.
retinaculum:
a hook-like structure to which another structure is tethered; in orchidaceae and asclepiadaceae, the structure to which
pollen
masses are attached; in acanthaceae, the
persistent
stalk of an
ovule
.
retrorse:
directed backwards or downwards. cf.
antrorse
.
retuse:
with a very blunt and slightly notched
apex
.
revolute:
rolled downwards or backwards.
rhachilla:
the secondary
axis
of a
decompound
leaf or
inflorescence
rhachis:
the
axis
of a
compound
leaf or
inflorescence
.
rhipidium:
an
inflorescence
of cymose units, the lateral branches developed alternately in opposite directions.
rhizoid:
a thread-like, unicellular absorbing structure, occurring in fern
gametophyte
s and in some non-
vascular
plants.
rhizome:
an underground
stem
, usually growing horizontally.
rhizophore:
in selaginella, a leafless
stem
that produces roots.
rhomboid:
quadangular, with the lateral angles
obtuse
.
root:
a unit of the axial system of a plant which is usually underground, does not bear leaves, tends to grow downwards and is typically derived from the
radicle
of the
embryo
. see
adventitious
.
rootstock:
a short, erect, swollen structure at the junction of the root and shoot systems of a plant.
rostellum:
a
beak
-like upward extension of the
stigma
in orchidaceae.
rosulate:
clustered into a rosette.
rotate:
circular and flattened, e.g. of a
corolla
with a very short tube and spreading
lobes
.
ruderal:
growing in waste places.
rudimentary:
poorly developed and not functional. cf.
vestigial
,
obsolete
.
rugose:
deeply wrinkled.
rugulose:
covered with minute wrinkles.
ruminate:
mottled in appearance, e.g. of bark, or of the food reserves in a
seed
.
runcinate:
deeply
lobed
and with the
lobes
slanted away from the
apex
.
runner:
a slender,
prostrate
or trailing
stem
which produces roots and sometimes erect shoots at its
nodes
.
