Obtuse – blunt-tipped (usually in the context of a leaf).
Opposite – (usually leaves) arising in opposite pairs on the stem.
Opposite
Oval – leaf shape. Ovate is oval in outline.
Ovary – structure containing the ovules, or immature seeds.
Ovoid – egg-shaped.
Palmate – leaf with finger-like lobes arising from the same point.
Panicle – branched inflorescence.
Pappus – tuft of hairs on a fruit.
Parasite – plant that derives its nutrition entirely from another living organism.
Pedicel – stalk of an individual flower.
Perennial – plant that lives for more than two years.
Perfoliate – surrounding the stem.
Perianth – collective name for a flower’s petals and sepals.
Petals – inner segments of a flower, often colourful.
Petiole – leaf stalk.
Pinnate – leaf division with opposite pairs of leaflets and a terminal one.
Pod – elongated fruit, often almost cylindrical, seen in pea family members.
Pollen – tiny grains that contain male sex cells, produced by a flower’s anthers.
Procumbent – lying on the ground.
Prostrate – growing in a manner pressed tightly to the ground.
Pubescent – with soft, downy hairs.
Ray – one of the stalks of an umbel.
Ray floret – one of the outer florets of a composite flower.
Receptacle – swollen upper part of a stem to which the flower is attached.
Recurved – curving backwards or downwards.
Reflexed – bent back at an angle of more than 90 degrees.
Rhizome – underground, or ground-level, stem.
Rosette – clustered, radiating arrangement of leaves at ground level.
Saprophyte – plant that lacks chlorophyll and which derives its nutrition from decaying matter.
Sepal – one of the outer, usually less colourful, segments of a flower.
Sessile – lacking a stalk.
Shrub – branched, woody plant.
Spadix – spike of florets as seen in members of the genus Arum.
Spathe – large, leafy bract surrounding the flower spike as seen in members of the genus Arum.
Species – division within classification that embraces organisms that closely resemble one another and that can interbreed to produce a viable subsequent generation.
Spreading – branching horizontally (in the case of a whole plant) or sticking out at right angles (in the case of hairs).
Stamen – male part of the flower, comprising the anther and filament.
Stigma – receptive surface of the female part of a flower, to which pollen adheres.
Stipule – usually a pair of leaf-like appendages at the base of a leaf.
Stolon – creeping stem.
Style – element of the female part of the flower, sitting on the ovary and supporting the stigma.
Subspecies – members of a species that possess significant morphological differences from other groups within the species as a whole; in natural situations, different subspecies are often separated geographically.
Succulent – swollen and fleshy.
Tendril – slender, twining growth used by some plants to aid climbing.
Tepals – both sepals and petals, when the two are indistinguishable.
Thallus – the body of a plant in species where separate structures cannot be distinguished readily.
Tomentose – covered in cottony hairs.
Trifoliate (or trefoil) – leaf with three separate lobes.
Truncate – ending abruptly and squared-off.
Tuber – swollen, usually underground, part of the stem or root.
Tubercle – small swelling.
Umbel – complex, umbrella-shaped inflorescence.
Whorl – several leaves or branches arising from the same point on a stem.
ATTRACTIVE THOUGH MANY OF them may be, flowers are not produced to delight the human eye. Their role is strictly functional – they are the plant’s sex organs, there to produce sex cells and ensure the maximum chance of successful fertilisation taking place.
BASIC FLOWER STRUCTURE AND FUNCTION
In a few species, male and female sex cells are borne in separate flowers, or even on different plants, but in most cases they appear together within the same flower. Male sex cells are contained within pollen, tiny grains that are produced by structures called anthers and borne on slender stems referred to as filaments; collectively, anthers and filaments are referred to as stamens. The female part of most flowers comprises the ovary, containing the female sex cells, above which is borne the stigma (which receives the pollen) carried on a stem called the style.
Some plants, such as grasses and catkin-bearing shrubs, employ the wind to carry their pollen to others of the same species. Vast quantities of pollen are required to achieve a successful outcome with such a random process. Most other species adopt a more targeted approach and use the services of animals – insects in almost all cases – to transfer pollen. In exchange for a meal, in the form of nectar, insects inadvertently carry pollen on their bodies to the next flowers they visit; with any luck, a neighbouring plant of the same species will be visited while pollen still persists. In almost all species, flower structure has evolved to avoid self-pollination and to maximise the chances of cross-pollination – pollen being transferred to visiting insect pollinators and received from other plants by the same agents.
Bumblebees, and bees generally, are the classic insect pollinators. They visit flowers in search of nectar and unwittingly acquire a dusting of pollen, which is slightly sticky, on their hairy bodies; this is then carried to subsequent flowers they visit.
Cross-section through a typical