398 



RHIZOBOLACE^E. 



[Hypogynous Exogexs. 



Order CXLIII. RHIZOBOLACE.E.— Rhizobols. 



Rhizobolea?, DC. Prodr. 1. 599. (1824); Cambessedrs in Aug. St. Hit. Fl. Bras. Merid. 1. 322. (1827); 



Endl. Gen. ccxxxi. 



Diagnosis. — Guttiferal Exogens, with digitate opposite leaves, symmetrical flowers, equi- 

 lateral pietals, sessile stigmas, solitary seeds, and an embryo with an enormous radicle. 



Trees of very large size. Leaves opposite, digitate, coriaceous, with a jointed stalk 

 and no stipules. Flowers large, regular, arranged in racemes, with their stalks jointed 



at the base and below the apex. 

 Sepals 5 or 6, more or less combined, 

 imbricated in aestivation. Petals 5 to 

 8, equal-sided but unequal, tliickish, 

 arising along with the stamens from 

 a hypogynous disk. Stamens ex- 

 tremely numerous, slightly monadel- 

 phous, arising in a double row from 

 a disk, the innermost being shorter 

 and often abortive ; anthers roundish, 

 2-celled, opening lengthwise. Ovary 

 superior, 4 or 5, or even many-celled ; 

 styles as many as the cells ; stigmas 

 minute ; ovules solitary, attached to 

 the axis by their middle, semianatro- 

 pal, with the foramen uppermost. 

 Fruit formed of several combined 

 nuts, part of which are sometimes 

 abortive ; each nut indehiscent, 1- 

 seeded, 1 -celled, with a thick double 

 putamen. Seed reniform, without 

 albumen, with a funicle which is di- 

 lated into a spongy excrescence ; 

 radicle very large, constituting nearly 

 the whole of the almond-like substance 

 of the nut, with a long 2-edged cauli- 

 cle, having two small cotyledons at 

 the top, and lying in a furrow of the 

 radicle. 



This very distinct Order De Can- 

 dolle thought allied to Soapworts in its 

 hypogynous flowers and its fruit ; and 

 especially to ^Esculus on account of 

 its opposite compound palmate leaves ; 

 but hi that genus the radicle is small, 

 and the cotyledons very large, while 

 in Rhizobols the radicle is enlarged, 

 and the cotyledons small. It how- 

 ever appears to be with Guttifers 

 that Rhizobols best agree. " In 

 these two Orders we find the leaves 

 opposite and articulated at their base, 

 hypogynous petals, a similar aestiva- 

 tion, numerous hypogynous stamens, 

 and exalbuminous seeds. The large 

 flowers of Caryocar call to mind those 

 of most Guttifers ; its inflorescence is 

 nearly that of Moronobea ; its fruit has 

 a relation to that of Mammea, and 

 presents, in that genus, as in several 

 others of the same Order, a single 

 seed in each cell." — Camb. in Aug. 

 St. II. Fl. Bras. 1. 323. Endlicher 

 traces a resemblance between them 



Fig CCLXXX. 



Fig CCLXXXI. 



Fig. CCLXXX. — Anthodiscus trifoliatus. 1. a flower bud ; 2. a flower ; 3. a perpendicular section 

 of the pistil. 

 Fig. CCLXXXI.— Caryocar butyrosum ; a section of one of the lobes of its fruit. 



