510 NATURAL HISTORY OF PLANTS. 



rarely 5-partite, free, often accompanied by oppositipetalous stami- 

 nocles. Stigma penicillate (6 genera). 



III. Bo3HMERiE/E. — Unarmed plants ; leaves opposite or alternate. 

 Female perianth free or adnate, adherent to the ovary, sometimes 

 (very frequently) tubular, sometimes very short or absent 

 (16 genera 1 ). 



IV. Parietarie/e. — Unarmed plants ; leaves always alternate 

 and quite entire. Flowers diclinous or polygamous. Inflorescences 

 (at least the females) possessing two or more herbaceous bracts. 

 Female perianth tubular free (5 genera 2 ). 



V. FoRSKOHLEiE. — Plants unarmed or sometimes covered with 

 indurated hairs ; leaves alternate or opposite. Flowers diclinous, 

 often involucrate. Female perianth tubular or absent (5 genera). 



Here we see the most variable characters that allow us to divide 

 the order into tribes or series. The other variable characters of less 

 importance, on which the genera and smaller divisions are founded, 

 are as follows. The stem may be woody or herbaceous, erect or 

 rooting. The leaves may be opposite or alternate, symmetrical or 

 unsymmetrical at the base ; and we often find inequality between the 

 two opposite leaves or two adjacent alternate leaves, the smaller 

 sometimes aborting completely. The venation is pinnate ; or the 

 blade may be tricostate or triplicostate 3 at the base. The leaves, 

 moreover, like the other organs, are glabrous or covered with hairs, 

 which, again, may be of three kinds : simple non-urticating ; simple 

 and urticating, glandular at the base ; capitate pericellular, non- 

 urticating. 4 Cystoliths 5 are also usually present in the blade, pre- 

 senting pretty constant variations in arrangement and form ; the 

 latter may be rounded, oblong, fusiform, linear, or more rarely 

 stellate. The stipules are sometimes lateral, sometimes axillary, 

 cauline or petiolar, free or united in pairs for a variable distance, 

 caducous or persistent. The floral cymes are simple or ramified, 

 solitary or grouped into simple or compound racemes or spikes, 

 symmetrical or unilateral. The axis of the general inflorescence is 



1 Reduced by us to 15 by restoring Cliama- insertion of the petiole; in a 3-plicostate leaf 

 baina (B. squamigera) to Bcehmeria. (folium S-plinervium) they are given off a little 



2 Reduced to 3, by uniting Gesnouinia and above the insertion." (Wedd., Prodr., 34.) 

 Helxine to Parietaria. 4 See p. 499, note 3. 



3 " In a Z-costate leaf (folium Z-nervium) the & Wedd., in Ann. Sc. Nat., ser. 4, ii. 267 ; 

 basilar ribs spring from the midrib at the very Mono<]>:, 10. 



