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developed as a petal, so-called. When there are five stamens in the festoon, the central stamen must be regarded as an interstaminal lobe, analogous to interpetiolar stipules-to the intersepaline lobes in some species of Campanula, in Nemophila, and in Potentilla itself (the socalled epicalyx), or to the interpetaline lobes of the corolla of Soldanella. *

I have not been able to examine any of the nearest allies of Potentilla fruticosa. P. glabra is grown in the Botanic Garden here, but has not flowered for some years. In Potentilla rupestris, however, I have found an andræcium in all respects similar to that of P. fruticosa ; and, from Lindley's description of the stamens of P. arguta, an ally of P. rupestris, as “ about 25, filaments inserted on the margin of a fivelobed glandular disk which surrounds the base of the receptacle(Bot. Reg. n. 1379), I suspect that the same arrangement occurs there also.

In connection with the foregoing investigation, I have been led to examine the staminal arrangements in a considerable number of species of Potentilla, in all about twenty-nine. The staminal arrangements in these species may be reduced under three heads or types.

Type I., where there are 20 stamens (16 where the flower is 4-nary): one superposed to each sepal, one to each petal, and one on either side of each petal (Plate LII. Fig. 1). This is, apparently, by far the commonest arrangement in the genus, as indeed in the whole family Rosacea.

Type II., where there are 30 stamens. Differing from the last by having three stamens, instead of one, in front of each sepal (Plate LII. Fig. 2). This occurs in the forms falling under P. hirta of De Candolle’s ‘Prodromus.'

Type III., where there are 25 stamens (arranged in five festoons, extending from petal to petal). Differing from Type II. chiefly in the absence of oppositipetalous stamens (Plate LII. Fig. 3). This occurs in P. fruticosa, P. rupestris, and probably in several others.

* The corolla of Soldanella presents ten lobes, alternately trifid and entire. The five trifid lobes are the petals; the five entire ones the interpetaline lobes. The petals, soon after their appearance, become connate, forming a gamopetalous corolla, with five entire lobes. Some time after this, the interpetaline lobes appear as projections of the margin of the corolla, in the centre of each interpetaline sinus ; and lastly, the lateral lobes of the petals appear. The development here corresponds, of course, to a basifugal evolution of leaf-lobes, and differs in this respect from what occurs in the compound stamens of Potentilla, which would correspond to a basipetal one.

I have found it convenient, for the purposes of description, to employ the term parapetalous for those stamens which occur one on either side of each petal; antisepalous, for the stamen or stamens in front of each sepal; and antipetalous for the stamen or stamens in front of each petal.

The following is a list of the species examined by me, named and numbered according to Lehmann's ‘Revisio Potentillarum' (Nov. Act. Acad. xxii. Suppl.). In determining some of the species I have had great difficulty, which will be understood by any one who has had to do with this most troublesome genus. The names to which I have affixed the mark (?) are to be looked upon as only approximately correct.

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III.

P. fruticosa, L. ... ... .......
P. ambigua, Jacquemont ......
P. tridentata, Sol. ...........
P. bifurca, L......................
P. sericea, L. (?) ............
P. stolonifera, Lehm. ....
P. rupestris, L. ..............
P. Pennsylvanica, L. ........
P. peduncularis, Don .........
P. palustris, Scopol. (Com. palustre, L).
P. chrysantha, Trev. (?)......
P. Taurica, Will. (?).....
P. recta, L., B. pallida (?).
P. hirta, L. (?) ..........
P. umbrosa, Stev.
P. Nepalensis, Hook...........
P. Calabra, Tenore............
P. argentea, L. ...........................
P. inclinata, Vill. .....
P. tomentosa, Ten. (?)..
P. maculata, Pourret (P.alpestris, Hall.)
P. opaca, L. .......
P. alba, L. ... ... .....
P. Fragariastrum, Ehrh.
P. atrosanguinea, Lodd.
P. elatior, Schlecht. (?)
P. Tormentilla, Sibth.
P. reptans, L. ...
P. anserina, L. ................

........

98 103 104 106 111 125 128 147 153 156 158 182 186 190

...

.............

Flowers

stal

nens.

Parapetalous

Of the species, in the foregoing list, with andræcia falling under Type I., the following are those which exhibit a tendency to vary, either by multiplication or reduction in the number of stamens :

A. Species exhibiting a tendency to multiplication in the number of stamens :

P.bifurca, L. Two flowers were examined ; one was normal, while in the other one of the antisepalous stamens was replaced by two slightly connected by their bases.

P. peduncularis, Don.
Number of Parapetalous

Antisepalous

Antipetalous stamens.*

stamens. examined.

5 .......... 10 ......... 1,1, 1, 1, 1 ......... 1,1,1,1, 1
2 ......... 10 ......... 1,1,1,1,1 ......... 1,1, 1, 1, 2

...... ......... 1,1,1, 1, 2 1,1, 1, 1, 1
1 .........

10 ......... 1,1, 1, 1, 2 ......... 1,1,1, 1, 2 1 ......... 10 ......... 1, 1, 2, 1,2 ......... 1, 1, 1, 1, 2 P. Calobra, Tenore. Number of

Antisepalous

Antipetalous Flowers examined.

stamens.

stamens.
......... 10 ......... 1,1,1,1,1 1,1,1,1, 1
......... 10 ......... 1, 1, 1, 1, 2 ......... 1,1,1,1,1

......... 1,1,1,1,1 ......... 1,1,1, 1, 2

......... 1, 1, 1, 1,2 ......... 1, 1, 1, 1,0 1 ......... 10 ......... 1,1,1,1,2 ......... 1,1, 1, 1, 2

1 ......... 10 ......... 1,1,2, 1,0 ......... 1,1,2, 1, 2 P. inclinata, Vill. (var. subseptenata ?). Flowers

Antisepalous

Antipetalous

stamens. 5 .........

......... 1, 1, 1, 1, 1

1,1, 1, 1, 2 .......... 1,1,x,1,2

1, 1, 1, X, 2

.... 1,x,l,x,x
10 ......... 1,1, 1, 2, 2

10 ......... 1, 1, 2, 2, 2
.... 10 ......... 1, 2, 1, 2, 2 .....
.........

10 ......... 1, 1, 2, 1, 2 .................. * In this and the succeeding tables, wherever the number of antisepalous or

.........

Number of

Parapetalous

examined.

stamens.

stamens.

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The mark x indicates a partial resolution of a stamen into two, the filament bearing two anthers.

It will be seen from the above that, while P. peduncularis and P. Calabra have a tendency to vary, both in the antisepalous and antipetalous stamens, P. inclinata varies only in the antisepalous ones. In the last-mentioned species, it is remarkable how frequently a partial or complete resolution of an antisepalous stamen into two takes place.

B. Species exhibiting a tendency to reduction in the number of stamens :

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P. opaca, L. (P. intermedia, Nestler). Six flowers were examined ; four were normal, while the other two each wanted one antipetalous stamen.

P. Fragariastrum, Ehrh. In this species a great number of flowers have the andræcium reduced to the 10 parapetalous stamens. Of better-developed andræcia, I have noted the following :

antipetalous stamens is indicated by five figures, these five figures represent the number of stamens in front of the five sepals or five petals respectively, and are noted down consecutively, as they may be read off on looking round the flower.

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10 ..................

...........

ovoco er

.........

1 ......... 10 ............... ..................... It is to be observed that in these reductions in the number of stamens, the antipetalous evidently disappear more readily than the antisepalous ones. This is what might have been expected, as the antipetalous stamens are the younger.

Of the species falling under Type II., those which I have examined are all variable in the number of stamens; and the tendency is almost always towards a reduction in the number. In a few flowers only is a tendency to multiplication of the antipetalous stamens to be observed. I have named with some hesitation the forms occurring in the Botanic Garden ; but they certainly all come under P. hirta of De Candolle's • Prodromus.'

P: Taurica, Willd. (?).
Number of

of
Flowers

Parapetalous

Tarapetalous examined.

stamens.

stamens.

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Antisepalous

Antipetalous
stamens.
3, 3, 3, 3, 3
3, 3, 3, 3, 2
3,3,3,2, 2
3, 3, 2, 3,2
3, 3, 2, 2, 2
3, 2, 3, 2,2 .......
3, 2, 2, 2,2 ...............

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