116 
Ofye Slower (Brower 
The Opening of Flowers. 
Willard N. Clute in Gardeners’ Chronicle. 
T HERE is probably no more interesting 
chapter in botany than that which con- 
cerns the opening of flowers. The 
casual observer noting the general resump- 
tion of activity by the world at large as the 
day breaks is likely to jump to the conclu- 
sion that flowers follow the general custom of 
opening with the advent of day and closing 
as night approaches. It is true that many 
plants have this habit, but it is far from the 
rule among plants. In fact, the phenomena 
of the opening and closing of flowers, or 
anthesis, as it is called, are extremely com- 
plicated and call for the best efforts of the 
botanist to explain. Just as the form, color 
and odor of flowers have been modified or 
even developed with reference to pollinating 
insects, so the time at which flowers open 
and the length of time they remain in this 
condition is determined by many extraneous 
agencies, many of which may possibly not be 
known at present. 
Not only is there much variation in the 
time at wh' h flowers open and close, but 
the greatest diversity exists as regards the 
length of time the individual flowers remain 
open. Certain orchids, if unpollinated, may 
remain open for six weeks or more and in 
general the absence of pollination tends to 
lengthen the life of the flower. Tulips, 
Easter Lilies and the like may be made to 
remain open for some time longer than they 
naturally would if pollination is prevented. 
Contrasted with these examples is a little 
weed, common in cultivated grounds which 
is known as “ flower-of-an-hour ” because its 
blossoms do not remain expanded much 
longer than the period indicated in the com- 
mon name. The blossom of the wild grape 
is still more remarkable, for just as the bud 
expands and the flower seems about to open 
the whole corolla falls off and thus the 
flower, though exposing stamens and pistils, 
can in a certain sense be said not to open at 
all. The garden plant called okra, though it 
ordinarily opens its flowers, may, on occa- 
sion, follow the example of the grape, and it 
is but a step from these to cleistogamous 
flowers like the summer flowers of some 
violets which entirely lack petals, and though 
perfecting much seed, always remain bud- 
like. 
In ordinary flowers some days usually 
elapse between the time the petals first un- 
fold and the date at which they wither and 
fall from the plant. The corolla, in the least 
interesting forms, remains continuously open 
until anthesis is past, but in others the flow- 
ers may close temporarily several times in 
response to moisture, lowered temperature, 
darkness or possibly other things. 
The opening of our early spring flowers, 
such as Crocus and Dog-tooth-violet, is fre- 
quently determined solely by temperature. 
If the temperature of the air and soil rise 
above a certain point they seem obliged to 
open. In fact, the same phenomena seem to 
govern the very production of such flowers 
and it has been found possible in many cases 
to ascertain the exact number of heat units 
necessary to produce a given blossom. It is 
a matter of common knowledge that the 
first flowers of any kind do not appear just 
anywhere. We must seek the earliest in the 
sunny and sheltered nooks where the re- 
quired number of heat units are first re- 
ceived. 
Temperature, however, may cause the 
closing of flowers, as we see in the case of 
the Waterlily, which, though it opens its 
flowers as soon as the day breaks, closes by 
mid-day. The same is true of Morning 
Glories, and possibly of other flowers that 
open late in the day and last until the next 
morning. That it is really temperature that 
causes the flowers of Morning Glory, Four 
O’clock and the like to close seems proven 
by the fact that late in the year, when the 
temperature has lessened, these flowers re- 
main open all day and the Morning Glories 
become all day glories. 
The effects of light upon the opening of 
some flowers are very marked. Waterlilies, 
picked in the early morning before they 
have opened and kept in the dark will open 
whenever brought to the light. Thus one 
may decorate the house with full-blown 
Waterlilies at evening. The dandelion, also, 
is very sensitive to the light and refuses to 
open unless the day is sunny. Often a few 
hours of cloudy weather in the middle of 
the day will cause the flowers to close. Sir 
John Lubbock, experimenting with these 
plants, found that if a blooming dandelion 
in a pot was exposed to bright lamp-light it 
would remain open all night. 
Darkness also apparently has an effect 
upon the opening of flowers, as in the Night 
Blooming Cereus and various other cacti 
which commonly do not unfold their petals 
until well along toward midnight. There 
are a host of other blossoms whose main 
period of bloom is during the hours of dark- 
ness. Many of these have common names 
that indicate the fact, as Four O’clock, Even- 
ing Primrose, Night Flowering Catchfly, 
Pretty-by-night, and the like. Flowers of 
this kind commonly remain open until the 
sun is well up and seldom open the second 
time. 
That darkness like temperature, may have 
opposite effects upon different flowers is seen 
in the fact that it is usual for many blos- 
soms to close as night approaches. This is 
so common a phenomenon that its very 
commonness gains it little attention. It will 
probably be difficult for one to name off-hand 
a flower that does close at night. Of this 
class, however, is the Day Lily, and so is the 
Daisy, whose name, literally the day’s eye, 
is truly significant. 
The amount of moisture in the air is also 
at times sufficient to influence the opening 
of flowers. The scarlet pimpernel, a com- 
mon weed with tiny red blossoms, is known 
in some sections as “ poor man’s weather 
glass.” Its flowers are so sensitive to mois- 
ture that they invariably close with the rise in 
humidity that betokens a storm and some 
hours in advance of it. Thechickweed, com- 
mon in cultivated grounds everywhere, is said 
to have the same habit. Many other flowers 
close in time to escape an actual wetting by 
the rain, while still others, though they do 
not close, are able to assume positions that 
keep the raindrop out of the flowers. The 
wild geranium turns its blossoms upside down. 
It is doubtless a fact that many of the 
phenomena of anthesis attributed to tem- 
perature, light and the like may, in the last 
analysis, turn out to be in response to the 
visits of insects. For instance, many of the 
flowers that open at dusk do so because 
they are pollinated by crepuscular insects. 
Further support is given this theory by the 
fact that many of these give out a fragrance 
at dusk and at dawn only, when such insects 
are abroad. It is hard, however, to reconcile 
the behavior of the oyster plant and goat’s- 
beard with any theory of adjustment to in- 
sects, for they close at exactly the time when 
insect visitors are most abundant. The 
goat’s-beard, in fact, has received the com- 
mon name of John-go-to-bed-at-noon because 
the flowers close so promptly at mid day that 
one could almost set his watch by them. 
It is a noticeable fact that flowers most 
affected by the agencies mentioned are all 
of the kind known as entomophilous, that is, 
insect pollinated flowers, since they open for 
the express purpose of receiving insect visits. 
It is likely that all the responses they 
November, 1919 
make to temperature, light and the like are 
really made with pollination as the ultimate 
end in view. Finding, however, that these 
phenomena are so intimately related to the 
flight of insects that they can be used as 
guides they have apparently been adopted. 
If an insect, for instance, does not emerge 
from its cocoon until a certain degree of 
heat is received and does not roam abroad 
unless the day is fair, the flower that is ad- 
justed to the same amounts of heat and light 
is certain to be in condition to be pollinated 
when the insect is flying. It may be pos- 
sible to trace similar adjustments through 
all the variations in anthesis throughout the 
world of plants. 
THE PEONY. 
The Twenty Best Peonies. 
In Bulletin of Peony News No. 7, is- 
sued by the American Peony Society, 
A. P. Saunders, Secretary, is a table d 
giving the results of the sending out of : 
rating lists on Peonies. About forty- 
five marked lists were returned and we I 
have selected below the twenty with 
highest marks. While these twenty | 
need not necessarily be considered the 
best 20 varieties, yet they are at least 
the best ones well known to the Peony - 
enthusiasts throughout the country. 
Doubtless there are many fine varieties 
that would score equally well if they 
were equally well known. 
The first column of figures is the 
number of votes cast for the variety 
opposite. The second column gives 
the average and the columns following 
give the votes in detail. The grading i 
is based on 10 as the highest excellence, J 
9 of high quality, 7 to 8 of fairly good 
quality, and anything below 5 indicat- 1 
ing a variety not worthy of cultivation. 
It will be noted that the twenty selected 
from the long list given have no votes 
lower than 7 which is sufficient indica- 
tion of the high regard in which these 
20 selected varieties are held : 
</> 
<u 
e>o 
Votes 
in 
> 
u 
<v 
Detail 
z 
< 
10 
9 
8 
7 
Baroness Schroeder (Kel.) 
33 
9.1 
13 
12 
6 
2 
Elizabeth Barrett Browning (Brand) 
7 
9.5 
4 
2 
1 
Festiva Maxima (Miellez) . .. 
40 
9.3 
21 
10 
9 
Kelway’s Glorious (Kelway) 
9 
9.4 
6 
1 
2 
Lady Alexandra Duff (Kelway) 
20 
9.3 
11 
6 
2 
1 
La Fee (Lemoine) _ 
13 
9.2 
7 
3 
2 
1 
La France (Lemoine) 
20 
9.3 
9 
S 
2 
1 
I.e Cygne (Lemoine) _ 
23 
9.7 
18 
2 
3 
Mad. Emile Lemoine (Lemoine) 
28 
9.1 
11 
9 
8 
Madame Jules Dessert (Dessert). . 
19 
9.4 
10 
6 
3 
Martha Bulloch (Brand) 
10 
9.2 
4 
4 
2 
Mignon (Lemoine). 
11 
9.1 
4 
5 
1 
1 J 
M. (ulesElie (Crousse) 
33 
9.2 
13 
15 
4 
1 
Philippe Rivoire (Riviere) . 
Pleas’ Jubilee (Pleasi 
7 
9.3 
3 
3 
1 
11 
9.2 
4 
5 
2 
Sarah Bernhardt (Lemoine). ... . 
23 
9.2 
10 
8 
5 
Solange (Lemoine). 
23 
9.7 
15 
8 
Therese ( Dessert) . _ 
32 
9.7 
24 
7 
1 
Tourangelle (Dessert) .. 
18 
9.4 
9 
8 
1 
Walter Faxon (Richardson) _. 
19 
9.2 
7 
9 
2 
1 
The interest in Peonies has developed 
remarkably during the past season. 
The Peony is so old and well known 
that it is not difficult to convince 
flower lovers that they should grow 
some of the new and rare things. The 
improvements which have been made 
during the past few years have been as 
remarkable in Peonies as in other flow- 
ers and the end is not yet. 
