GROUP V. AXGIOSPER&LE J DICOTYLEDON KS. 543 



Order 3. OXALIDACE.E. Disc present as small glands at the 

 base of the antipetalous stamens, or of all of them : flowers actino- 

 morphic; formula Ko, Co, ( | 45 + 5), G^ ; the antipetalous 

 stamens are sometimes staminodial ; those which are opposite to 

 the sepals are the longest : ovules numerous ; fruit a capsule, or 

 more rarely a berry ; seed containing endosperm. Herbs, with 

 compound (ternate), generally exstipulate leaves. 



Oxalis Acetosella, the Wood-S3rrel, is frequent in woods; it contains 

 much potassium oxalate. The tuberous roots or underground stems of 

 some American species, as 0. esculenfa, crenata, and Depjyei, contain much 

 mucilage, and are used as food. Some species (e.g. O. gracilis) show tri- 

 morphic heterostylism (p. 411) : others (e.g. O. Acetosella), have cleistoga- 

 mous flowers (p. 410). The leaves of Oxalis and Averrhoa show sleep- 

 movements : those of Biophytum are sensitive to touch. 



Order 4. BALSAMIXACE.E. Disc 0: flowers irregular, dorsiven- 

 tral ; formula Kb, (75, | 40 + 5, G ( - : the posterior sepal is 

 spurred, and the two anterior are small or absent : the anterior 

 petal is large : ovary 5-locular ; ovules numerous ; the fruit is 

 loculicidally septifragal, the valves separate elastically and roll 

 upwards, so that the seeds are projected to some distance ; seed 

 without endosperm. Herbs, with simple exstipulate leaves. 



Impatiens Noli-me-tangere, the yellow Wild Balsam, occurs in damp and 

 shady spots ; the ripe fruit flies open with violence at a touch. Impatient 

 Balsamina, an Indian species, is cultivated. 



Order 5. RuTACEjE. Disc usually annular : flowers usually 

 actinomorphic : gynseceum sometimes partially apocarpous, but the 

 styles are usually connate : seed with or without endosperm. There 

 are numerous oil-glands on the leaves and stems. 



Sub-order. E.CTE.E. The placentse project into the loculi of the ovary; 

 each bears 3 or more ovules : fruit a loculicidal 

 capsule : seed with endosperm. Ruta grateolens, 

 the Hue, has pentamerous terminal flowers, and 

 tetramerous lateral flowers. Dictamnus Fraxin- 

 ella has an irregular dorsiventral flower. 



Sub-order. AURANTIE^:. Gynseceum syncar- 

 pous : calyx gamosepalous : fruit a berry (p. 476) : 

 seed without endosperm. 



The genus Citrus has an indefinite number of 

 bundles of connate stamens (polyadelphous) (Fig. F|G - 351.-Diapram of 

 355 A), all belonging apparently to the aiitise- 



palous inner whorl : the carpels are usually more numerous than the 

 petals, and during ripening they become filled with a succulent tissue de- 



