284 



CALLITRICHACEiE. 



[Diclinous Exogexs. 



Order XCII. CALLITRICHACE^.— Starworts. 



Lavielle in Ann. Soc. Linn. Par. p. 

 ; Endl. Ixxxiv, ; Meisn. p. 336. 



DC. Prodr. 3. 71 ; 



Callitrichineae, Link. Enum. 1. 7- (1821) 

 Ed. pr. (1836 



Diagnosis.— -E'wp^or6iaZ aquatic Exoyens, with definite suspended anatropal ovules, and 



a supjerior radicle. 



Small aquatic herbaceous plants, with opposite, sunple, eutii'e leaves. Flowers axil- 

 lary, solitary, very minute. Flowers unisexual, monoecious, naked, with 2 fistular colom-ed 

 bracts. $ Stamen hypogynous, single, rarely 2 ; filament filiform, furrowed along the 

 middle; anther reniform, 1 -celled, 2-valved ; the valves openmg fore and aft. ? Ovary 

 sohtary, 4-cornered, 4-celled ; o^^lles sohtary, attached to the axis, 

 suspended, amphiti'opal ; styles 2, right and left, subulate ; stigmas 

 simple points. Fruit 4-celled, 4-seeded, indehiscent. Seeds peltate ; 

 embryo mverted in the axis of fleshy albumen ; radicle very long, 

 cm-ved, superior ; cotyledons very short. 



I have formerly remai'ked, that " the affi- 

 nity of this Order to other dicotyledons ap- 

 pears to be of the same nature as that borne 

 by Lemna to Monocotyledons : they each ex- 

 hibit the lowest degree of organisation known 

 in their respective classes." Brown considers 

 the Order allied to Hippurids : an opinion in 

 which Botanists seem disposed to concur. The 

 great objection to it is this ; Hippm-ids are a 

 reduced form of the exalbuminous Onagi-ads, 

 with the petals often absent, and the calyx 

 sometimes dimmished to what seems a mere 

 rim ; but in reality, in consequence of the 

 ovary being adherent, the whole of the tube 



of the calyx as well as its rim remams adhering to the ovary, so that the calyx is not in 

 fact materially diminished ; but Starworts are absolutely destitute of a calyx and 

 are albuminous. These circumstances, and the unisexual flowers of the Order, seem to 

 point to a widely different station, and accordmgly, in the last edition of this work, it 

 was arranged among the Incomplete Orders — in the neighbom'hood of Moss weeds. 

 It must, however, be confessed that its relation to these plants is one of analogy rather 

 than of affinity. Nevertheless, EndUcher places it m the same situation, remarking, 

 however, that it is perhaps an aquatic form of Spm'ge worts. And in this he seems to 

 be right ; at all events it differs so little from that Order, except in its indehiscent fruit 

 and amphitropal ovules, that unless w^e should hereafter be able to employ internal struc- 

 ture for high systematical divisions, it is in the Euphorbial AUiance that this plant will 

 remain. It is doubtful mdeed whether it ought, in the present state of our knowledge, 

 to be regarded as an independent Order. 



Natives of still w-aters in Europe and North America. 



The uses are unknown. 



GENUS. 



Callitriche, L, 



Fig. CXCVI. 



Numbers. Gen. 1. Sp. 6, 



Ceratopliyllacece J 

 Position. — Euphorbiaccce. — Callitrichace^. 

 HaloragecB. 



Fig. CXCVI.— Callitriche vei-na. 1. a J* flower j 2. a ^ ; 3. a perpendicular section of the ripe fruit. 



