Taula de continguts:
Piperales, ordre de plantes florals que comprenen 3 famílies, 17 gèneres i 4.170 espècies. Juntament amb les ordres Laurales, Magnoliales i Canellales, Piperales forma el clade magnoliide, que és una branca evolutiva primerenca de l’angiosperma; el clade correspon a part de la subclasse Magnoliidae sota l'antic sistema de classificació botànica Cronquist.
Moltes espècies piperales són conreades ornamentals, inclosa la cua de sargantana (Saururus cernuus); Espècie de Peperomia; Anemopsis, del sud-oest d’Amèrica del Nord; Houttuynia, coberta terrestre d’Àsia; gingebre salvatge (Asarum); i vinyant espècies d'Aristolochia, conegudes com a pipa holandesa. Piper nigrum és la principal font del condiment picant conegut com a pebre negre (però també pebre verd o blanc).
Característiques comunes
Els membres de l'ordre Piperales solen trobar diverses característiques també en monocotiledònies, incloent-hi discrets feixos vasculars a la tija i tres parts florals. Tot i que hi ha membres llenyosos, aquest ordre és característicament herbàcia i té sovint nodes de fulles inflades. La reproducció per llavors és el principal mètode de dispersió d'espècies a Piperales, però la fragmentació de rizomes en la família de les cues de les sargantanes assegura la propagació vegetativa. El drupa és el tipus de fruita predominant a les Piperaceae, o de la família dels pebrots, mentre que els fruits secs caracteritzen les altres quatre famílies.
Famílies
Les Saururaceae, la família de la cua de les sargantanes, són originàries d’Amèrica del Nord i del sud-est asiàtic. Inclou cinc gèneres i sis espècies, la majoria d’herbes aromàtiques amb rizomes rampants (tiges horitzontals). Les plantes solen habitar en zones humides.
The largest family in Piperales is Piperaceae, which is pantropical and includes 5 genera and some 3,600 species, most of them in the large genera Peperomia and Piper (the black pepper genus). Saururaceae and Piperaceae are closely related. Their inflorescences (flower clusters) are slender, spikelike, and covered with inconspicuous closely appressed flowers. Even though individual flowers are small, the floral spikes are showy, and in several Saururaceae species the spikes resemble a single flower because of the expanded bracts that arise below the inflorescence. In Saururus the elongate cluster bends at its tip to suggest the fanciful appellation “lizard’s tail.” Other features common to most species of these two families include a sheathing leaf base, a lack of sepals and petals, bisexual flowers (stamens and carpels in the same flower), and the presence of one erect ovule per ovary chamber.
Aristolochiaceae, the birthwort family, includes about 590 species of woody vines, shrubs, and herbaceous species. Most species are distributed in the tropics of both hemispheres, though several genera are in the temperate zone. Compared with the flowers of other Piperales families, those of Aristolochiaceae are usually large, and some trap pollinating flies that are lured by unpleasant smells. Asarum and Saruma are herbaceous genera of the north temperate zone, most diverse in eastern Asia. Aristolochia includes more than 400 species of vines and herbs, many of them tropical. It is this group that is sometimes divided into two or four separate genera.
Lactoris fernandeziana, the only species in Lactoris (formerly of the family Lactoridaceae), is found on one island of the Juan Fernández Archipelago, off the coast of Chile. The leaves have a sheathing base, and the flowers occur singly or in small clusters along the stem. The flower stalks, or petioles, appear to arise from a sheathing leaf base that lacks a leaf blade. Lactoris pollen has been recovered in southern Africa from sediments dating back to the Late Cretaceous Epoch (100.5 million to 66 million years ago).
The former family Hydnoraceae is now a small subfamily of Aristolochiaceae, with seven species in two genera. They are terrestrial parasitic plants that lack leaves and chlorophyll. The large flowers have a single three-parted perianth whorl and an inferior ovary; they are foul-smelling and are pollinated by flies and beetles. Prosopanche occurs in Central and South America, and Hydnora occurs in Africa, Madagascar, and the Arabian Peninsula. The southern African Hydnora triceps grows exclusively on succulent species of Euphorbia.
