#pinna
- Drummond's wattle — A dwarf species of ornamental shrub, endemic to the southwestern regions of Western Australia, renowned for its outstanding structural elegance. Unlike many acacia species that develop phyllodes, Acacia drummondii retains its true leaves, featuring a fine, delicate, evergreen, bipinnate foliage of a deep green hue. The plant is distinguished during its flowering season by its atypical, cylindrical, and pendulous inflorescences (resembling catkins or tassels) of an intense canary-yellow, making it considered one of the most refined and decorative small species within the genus.
- Acaena pinnatifida — A species of perennial herbaceous plant in the Acaena genus, native to the temperate and subalpine regions of South America. The taxon stands out due to the deeply divided structure of its compound leaves, whose leaflets are deeply incised or pinnatifid, resembling miniature ferns. This unique foliar architecture not only enhances its aesthetic value but also represents an efficient structural adaptation for dissipating strong winds in its native habitats.
- Antehelix — A curved prominence of the external ear pinna, situated in front of and parallel to the helix, separated from it by the scaphoid fossa. This cartilaginous structure bifurcates in its upper part into two flexible crura that frame the triangular fossa, playing an essential role in capturing, reflecting, and guiding sound waves toward the external auditory canal.
- Arenga pinnata — The official binary name for the sugar palm, a large-sized palm species native to the tropical regions of South and Southeast Asia, belonging to the Arecaceae family. The plant is structurally characterized by long pinnate leaves and a robust trunk covered in black fibrous strands; it is utilized industrially for extracting sweet sap to produce palm sugar and bioethanol, as well as for its resilient fibers (ijon).
- Auricle — An anatomical pouch-like or small sac structure located on the upper part of each of the two cardiac atria (left and right auricles), serving to increase blood storage capacity. In zoology and comparative anatomy, the term also denotes the pinna of the external ear in mammals or a lateral prolongation in certain invertebrates.