642 



PLANTAOINACE^R. 



[Perigynous Exogens. 



Fig. CCCCXXIX. 



Order CCXLVI. PLANTAGINACEiE.— Ribworts. 



™ * • „ t„c< rv>> RQ (17891 — Plantaginese, R. Brown Prodr. 423. (1810); Endl. Gen. cxvi.; 

 V ^^^f^^^U^PlS^T'Barni W d Recherches sur le DtvcloppemenU «*. des 



Plantaginces. 



Diagnosis.— Cortusal Exogens, with stamens alternate with the petals, 1 style, and a straight 



inflorescence. 



Herbaceous plants, usually stemless, occasionally with a stem. Leaves forming 

 rosettes or in the caulescent species both alternate and opposite ; flat and ribbed or 

 taner and fleshy. Flowers in spikes, rarely solitary, usually Q , seldom by abortion $ ? . 



Calyx imbricated in aestivation, 4-parted, persis- 

 tent. Corolla membranous, monopetalous, hypo- 

 gynous, persistent, with a 4-parted linib. Stamens 

 4, inserted into the corolla, alternately with its 

 segments ; filaments filiform, flaccid, doubled in- 

 wards in aestivation ; anthers versatile, 2-celled. 

 Ovary composed of a single carpel, sessile, without 

 a disk, 2-, very seldom 4-celled, the cells caused 

 by the angles of the placenta ; ovules peltate 

 or erect, solitary, twin, or indefinite ; style sim- 

 ple, capillary ; stigma hispid, simple, rarely half- 

 bifid. Capsule membranous, dehiscing trans- 

 versely with a loose placenta bearing the seeds on 

 its surface. Seeds sessile, peltate, or erect, soli- 

 tary, twin, or indefinite ; testa mucilaginous ; 

 embryo lying across the hilum in the axis of 

 fleshy albumen ; radicle remote from the hilum, 

 inferior, or in some cases centrifugal. 

 Tbis is a croup regarding whose affinities the opinions of Botanists are unsettled. 

 Bv Jussieu ?t was considered apetalous, and placed near Amaranths and Chenopods, 

 the calyx being called bracts, and the corolla calyx ; but this is scarcely an admissible 

 explanation of the structure. I formerly stationed it near Leadworts, to which it 

 must be regarded as nearly allied ; but I was certainly wrong in associating it with 

 composite plants and their allies. Don was, I think, the first to suggest that it might 

 be connected with Primworts by means of Glaux, an apetalous genus belonging to that 

 Order Latterly M. Barneoud,\vho has particularly studied the subject, has suggested 

 that the supposed corolla is nothing more than a series of abortive stamens analogous 

 to the membranous cup of Gomphrenas and other Amaranths ; and he adopts the 

 opinion of Jussieu that the Orders of Amaranths and Chenopods are those with which 

 Ribworts ou-mt to be associated. In this opinion I cannot concur. There is nothing 

 to distinguish the corolla of Ribworts from the part so called in other plants, except its 

 thinness and want of vascular texture ; all corollas must, in a morphological sense, be 

 regarded as barren stamens ; and, moreover, the embryo and seed of Ribworts are 

 totally different from anything known in the Chenopodal Alliance. It appears to me 

 that Don's idea was correct, and that upon the whole the Order is a near ally ot the 



Primworts. , . . , , 



The ovary of Plantago does not present distinctly the appearance of a tree central 

 placenta But in reality the placenta is at first quite free, although eventually it is 

 pressed 'close to the sides of the ovary, and thus divides the cavity into 2 or more cells. 

 This is however, only a temporary contact, tor long before the seeds are ripe i the pla- 

 centa shrinks so much as to lose its adhesion with the sides of the ovary, and then it 

 becomes truly free. In Plantago arborescens it is, when ripe, continuous with the 

 stigma, and the two become loose and may be removed together, leaving the sides of 

 the ovary undisturbed. 



The tendency to diclinism is verv striking in the genus Littorella, and also occurs in 

 Bougueria ; it is not, however, perfect, for the male Littorellas have the rudiment of an 



° V Tk species are scattered over the whole world, in almost every quarter of which 



Fig. CCCCXXIX. 

 5. section of it. 



-Plantago lanceolata. 1. flower and bract ; 2. pistil ; 3. ovary cut across ; 4. seed ; 



