398 



RHIZOBOLACE^. 



[Hypogtnous Exogens. 



Order CXLIII. RHIZOBOLACEiE.— Rhizobols. 



Rhizoboleae, DC. Prodr. 1. 599. (1824); Camhessedes in Aug. St. Hil. Fl. Bras. Merid. 1. 322. (1827); 



Endl. Gen. ccxxxi. 



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

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

 Trees of very large size. Leaves opposite, digitate, coriaceous, vnth 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, 

 unbricated in aestivation. Petals 5 to 

 8, equal-sided but unequal, thickish, 

 arising along with the stamens from 

 a hypogjTious disk. Stamens ex- 

 tremely numerous, shghtly 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 theu' 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 neai'ly 

 the whole of the almond-like substance 

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

 cle, havmg two small cotyledons at 

 the top, and Ij'ing in a furrow of the 

 radicle. 



This very distinct Order De Can- 

 doUe thought allied to Soapworts in its 

 hypogynous flowers and its fniit ; and 

 especially to ^sculus on account of 

 its opposite compound palmate leaves; 

 but in 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, 

 hj^ogynous petals, a similar aestiva- 

 tion, numerous hypogj-nous stamens, 

 and exalbuminous seeds. The large 

 flowers of Caryocar caU 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 

 otliers of the same Order, a single 

 seed in each cell." — Camb. in Aug. 

 St. IT. Fl. Bras. 1. 323. EndUcher 

 traces a resemblance between them 



Fig. CCLXXX. 



CCLXXXI. 



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

 of the pistil. 

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



