Observations on the Perianth in Ranunculus auricomus and Anemone coronaria

Observations on the Perianth in Ranunculus auricomus and Anemone coronariaAuthor(s): W. B. TurrillSource: New Phytologist, Vol. 18, No. 8 (Oct., 1919), pp. 253-256Published by: Wiley on behalf of the New Phytologist TrustStable URL: http://www.jstor.org/stable/2428077 .

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W. B. Turrill. 253

OBSERVATIONS ON THE PERIANTH IN

RANUNCULUS AURICOMUS AND ANEMONE

CORONA RIA. By W. B. TUlnRILL, B.Sc.

[WITH IHREE FIGURES IN THIS TEXT.]

HE origin of the perianth in the Angiosperms has already been discussed from different poinits of view by Worsdell

(1) and Rendle (2) in an early volume of this journal and it is unnecessary to recall in detail the theories which are there debated. The two extreme views are that the perianth has been derived entirely and directly from either the bracts or the stamens. Compromising suggestions are that the calyx has beeni derived from bracts and the corolla from stamens, and that the perianth in some group or groups of plants has arisen by metamorphosis of bracts and in other groups by metamorphosis of stamens. Genera and species of Raniunculaceae have frequently been mentioned in the controversy, especially by those who have accepted the staminoid origin of the perianth, and it seems worth wlhile to record some observations made this spring on flowers of Rantunculus auricoinus and also to describe an anomalous specimen of Anemone coro?laIria recently received at Kew.

Ranunculus auricomnus is a species of buttercup common throu ghout a large part of E urope and kinown from most parts of the British Isles except the extreme north of Scotland. A large patch grows in the shade under a walnut-tree north of the Aroid House in Kew Gardens, and last May the opportunity was taken of making a careful examination of some hundreds of flowers. The results may be most convenienitly summarized as follows:-

1. The majority of the flower s haid no petals ( honley leaves of Prantl) or staminodes. In suoh flowers five sepals were con- stantly present.

2. The normally developed sepals were greenish-yellow with a deeper tinge of green towards the apex, or green with a yellow margin of gr eater or less width, they had no trace of a nectary and were always hairy on the back and glabrous oni thie inner (tupper) surface.

3. The fully developed petals were bright deep yellow in colour, quite glabrous on both surfaces, anid each wats provided on the inside a short distEance above the base with a small, oval- orbicular, shallow pit which served as a nectary.



254 W. B. Turrill.

4. The stamens had a relatively broad connective and 2-lobed anthers, each lobe havingtwo pollen-sacs and dehiscing longitudinally.

5. A few flowers were found which were funictionally female. These were usually situated loW down on the plants and were therefore more or less covered by foliage and by taller plants. Their stamens were very much r-educed in size and prodticed little or no pollen. Similar unisexual states of both Racnunculus bulbosus and R. acris have been found on the lawns at Kew.

6. A series of interesting transition stages between stamens and petals were found and a selection are here flgured. It will be noted that the filament is usuLally very short or entirely suppressed. Fig. la, is a normal stameni with two of the four pollen-sacs showing. Fig. 1, b represents a staminode from a flower with flve ordinary green sepals and no petals. The staminode was short, narrow, and showed clear indications of two anther-lobes each with two pollen-sacs which dehisced by a common longitudinal slit setting free a small amouint of pollen.

Fig. 1, c is very similar to the last but the pollen-sacs are not so well-developed and only a little incomplete pollen was found at the base. Fig. 1, d is a staminode from a flower with five sepals and one fully developed petal. One anther-lobe was complete and had two pollen-sacs which produced a small amount of pollen, the other was formed below but was replaced above by a small pocket.

Fig. I, e repr esenits a staminode from a flower with five sepals anid one normal petal. In side view it strongly recalls the honiey- leaves of species of Hellebotrus and Erauthis. No pollen was produced and both anther-lobes ended above in pockets.

Fig. 1,J is a staminode taken from a flower which also possessed flve sepals anid one normal and one nearly normal petal. A double pocket was present in the lower half and near the base there was an indicatation of a nectary.

Figs. 1, g and h are staminodes from a flower which also had five sepals and one normal petal. Some incomplete pollen grains were found near the margins.

Fig. 1, i is a staminode from a flower which also had four sepals and one normal petal. No pollen grains were found.

Fig. 1,j represents a staminode which may be termed a petal, for a nectary is present near the base and no pollen was produced though the remnant of one of the anther-lobes was present.

Fig. 1, k from a flower with flve sepals, is a petal with a well- formed nectary but with thickened ridges parallel to the margins in the lower half.



Ranunculus Aurkcomus and Anemone Coronaria. 255 Fig. 1, 1 represents a fully developed petal. 7. It was frequently noticed that when only four sepails were

present the place of the fifth was taken by a moi e or less normally formed petal. It was always the sepal innermost in the whorl which was thus replaced.

8. In one flower with four normal sepals and no normal petals oi' staminodes a perianth-leaf, half sepaloid, half petaloid, was found occupyinig the position of a fifth sepal and internlal to the others, Fig. 2, m. The lower part was green, externially hairy, and sepaloid, the upper yellow, glabrous, and petaloid. There wEas no trace of a niectory.

9. In one flower, wlhich unfortunately had partly fallen to pieces wheni gathered, one of the sepals was replaced by a leaf intermediate between a sepal and an involucral bract. It was greenish-yellow and hairy on the back onily, like the sepals, but was regularly lobed (Fig. 2, i).

Specimens of Anemitonie coroniarica with a fully developed sepal in the position of a segment of the involucre have several times been reported in cultivated plants, but no previous record has been found of the occurrence of this abnormality in wild specimens. Anemiionie coroniari(a is a native of South Eulrope and the Orient. In Palestine it is one of the commonest and most beautiful of the native flowers, and is probably the "lilies of the field" of the

D- 9 t LId \1

FIG. 1. RantuIncuilus auricomus. Tranisition forms between stamens and "petal," a, normal stamen, 1, normal " petal."



256 Ranunculus Auricomus and Anemone Coronaria.

FIG. 2. Ranulitctluts a?itGcom?ts. Hi Transition forms between "1petal' and IIsepal,' it, bract-like sepal.

Fig. 3. a A,emo?ze co;omYia

Dis'placenlient of "'sepal " into the involuct al whorl.

Bible. The majority of the flowers have from six to nine deep scar-let petaloid sepals and no petals.t From I to 6 cm. below the flower an involucre is situated and usually consists of three separate bracts whichl are deeply and irregularly lobed. Amonigst a consignmenlt of well dried sprecimelns of this species collected in Central Palestine by Capt. G. H1. Ogilvie was found one which shows a sepal, normal in" size, colour, vei,ation and i -iumentum, but alrising in the iiivolucral whorl 2 cm. below the remailiiiig nine sepals of the flower-, Fig. 3. One of two explanations is possible, that a sepal has become mispzlaced, its primordium having been left behFind when the pedicel above the bracts lengthened, or that an involucral Tract has become abnormally metamor"hosed into a sepal. The former seems the more probable becaLse three normal bracts are present ilt the involucral whorl in additioll to the sepal.

REFERENCES. 1. Worsdell. "The origin of the periaith of flowers." New Phytologist 2,

pp. 42, 116, 1903. 2. Rendle. "The origin of the perianth in seed-plants." I.c., p. 66. 3. Davis. Knuth's " Handbook of flower pollination." 2, pp. 28-29.



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Observations on the Perianth in Ranunculus auricomus and Anemone coronaria