Quillajaceae D. Don
~ Rosaceae-Quillajeae in older treatments
Habit and leaf form. Trees. To 15–20 m high. Leptocaul. Leaves evergreen; small to medium-sized (3–5 cm long); alternate; spiral; leathery; petiolate; non-sheathing; not gland-dotted; simple. Lamina entire; oblong to ovate (?); pinnately veined (?). Leaves stipulate. Stipules intrapetiolar; free of one another; small, scaly; caducous. Lamina margins entire, or serrate. Leaves without a persistent basal meristem.
Leaf anatomy. The mesophyll containing calcium oxalate crystals. The mesophyll crystals solitary-prismatic (with true styloids recorded).
Reproductive type, pollination. Plants hermaphrodite, or polygamomonoecious (the laterals male, the centrals female-fertile). Floral nectaries present. Nectar secretion from the disk.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in corymbs (these dense). The ultimate inflorescence unit cymose. Inflorescences terminal and axillary; dense corymbs, 3–5 flowered. Flowers bracteate; bi- bracteolate; small (to 15 mm in diameter); regular; basically 5 merous (with a few exceptional flowers); pentacyclic.
Perianth with distinct calyx and corolla; 10(–14). Calyx 5(–7); 1 whorled; briefly gamosepalous; blunt-lobed (the lobes broadly ovate). Calyx lobes markedly longer than the tube. Calyx regular; valvate; with the median member anterior. Corolla 5(–7); 1 whorled; polypetalous; contorted; regular; white; plain. Petals small, sessile.
Androecium 10. Androecial members maturing centripetally; free of the perianth; free of one another; 2 whorled. Stamens 10; diplostemonous; oppositisepalous; both alternating with and opposite the corolla members (5 inserted at the base of the disk, 5 alternating with them and inserted at the apices of the disk lobes); filantherous. Anthers dorsifixed; dehiscing via longitudinal slits; tetrasporangiate. The initial microspore tetrads tetrahedral. Tapetum glandular.
Gynoecium 5(–7) carpelled (the carpels antesepalous, sessile, tomentose). Carpels reduced in number relative to the perianth. The pistil 5 celled. Gynoecium syncarpous; semicarpous (the carpels proximally fused); superior. Carpel 10–50 ovuled (many). Placentation marginal (the ovules flattened). Ovary 5(–7) locular. Stigmas distal, along the revolute part of the style. Ovules sub- horizontal; biseriate; anatropous.
Fruit non-fleshy; an aggregate. The fruiting carpel dehiscent; a follicle (the 5 follicles stellately spreading, ventrally sutured). Dispersal unit the seed. Fruit 10–25 seeded (per follicle). Seeds long and broadly winged (in the upper part). Cotyledons 2; rolled.
Physiology, biochemistry. Saponins/sapogenins present (the powdered bark of Q. saponaria being used as a substitute for soap).
Geography, cytology. Neotropical. Temperate to sub-tropical. Brazil (Q. brasiliensis), Andean Chile and Peru (Q. saponaria).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Rosales. Cronquist’s Subclass Rosidae; Rosales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Fabales.
Species 2. Genera 1; Quillaja.
Economic uses, etc. Known as the Soap or Soapbark Tree.
Miscellaneous. This draft description by LW (2009) lacks information on anther development and pollen, embryology, and phytochemistry. It also needs pursuing further with special reference to features characteristic of Rosaceae.