opposite attached along an axis in pairs, each
member of the pair opposite the other. See example.
palmate. Radiating out from a common point at
angles to eachother, somewhat like fingers on a hand. Opposed to pinnate,
where the alignment is like the barbs on a feather, in two opposite parallel
rows. See example.
peduncle. The stem of a flower or fruit.
perfect Of a flower containing male and
female parts, hermaphroditic.
petiole. The stem of a leaf. Its absence makes
the leaf sessile. The stem of a flower or fruit (the
same thing since flowers turn into fruits) is a peduncle.
petiolule The stem of a leaflet.
pinnate. Spreading out on the two sides of an
axis like the barbs of a feather, or the leaflets of trees like the
samara. A dry fruit, like an achene, but equipped
with a wing or wings.
schizocharp A fruit that splits into parts when ripe,
such as the maple's, which breaks in two.
serrate Of teeth or having teeth like a
saw's (regular and somewhat pointed towards the tip of the leaf).
sessile Lacking a stem (petiole, peduncle, &c),
sinus In the margin of a leaf, a
concave, scooped out area.
spine A spine is pointy like prickles and thorns,
but unlike them is a modified leaf or stipule. The structures on Black Locust
(Robinia) are spines.
stigma The organ atop the pistil which receives
thorn Thorns are modified twigs, and hence woody
and present on twigs, branches or trunk. Hawthorns (Crataegus) and
Honey Locust (Gleditsia) have thorns. Compare to Prickle and
zygomorphic Bilaterally symmetrical, with a
plane of symmetry dividing it into to halves which are mirror images. Eg.,
the flowers of orchids, or the human body, or a bed.