120 



;it the same time, are (inite handsome, frajirant. and stay in bloom a week 

 or more. It is curious that finding the plant in a certain locality one 

 season is no sij^n that it can lie lonud there next year. 



Tfiraxdcuin Tuni.rdcinii (L.i Kcrst. While watching the effects of tem- 

 perature on the dandelion in .fune a nundier wei'e found which were not 

 producing pollen, the heads were perfect in every way. ))ut had no pollen 

 on the styles or liranches of the stij^mas when the bees Avere excluded. 



The connate anther-tubes, which were of the normal form in all stages 

 of development, were examined iindei- the microscope and not a grain of 

 pollen found in them. The sterile head.s were of a uniform pale yellow 

 and lacked the golden tinted center of the fertile heads found growing 

 near liy. Bees indifferently passed from one kind to tlie other. Seed was 

 foiniid on the sts'rile licads, l>ut tlxMc were more al)ort('d achenes than 

 usual. 



The dandelion is very sensitive to change of temperature, while the 

 absence of sunshine has very little elfect. Early in the season the same 

 heads may be exposed as often as three days in succession, and the in- 

 voluci e not ),e opened f(jr more than two or three hours at any one time. 

 As the temperature increases they stay exposed from early morning until 

 shut up by the falling temperatui'e of the afternoon, and may not open 

 again next day. 



Riiflliii sin'ijens L. produces a large crop of cleistogamous flowers 

 during lute summer and autumn. The flowers are clustered in the axils 

 and hidden by the long segments of the calyx. The change from con- 

 spicuous to concealed flowers involves more than a change from gamo- 

 petalous to apetalous. The stamens are reduced in length to that of the 

 ovary with a small pollen-producing surface at the tip, which is in close 

 proximity to the sessile stigma. The resiilting ci!i)suli s are numerous and 

 well filled with seed. 



Ftilcatd coiiKjsd (L.) Kuntze sends forth long, slender, stoloniferous 

 runners in early simimer that produce apetalous flowers before the con- 

 spicuous blooms appear. Not only is the form of the flower quite differ- 

 ent from that of those coming later, but the early, ovoid, single-seeded, 

 fleshy pod is very unlike the three-seeded, bean-like pod of the later 

 flowers. The mature single-seeded pods are found on or near, the ground 

 after the conspiciious flowers have come into bloom. 



If ().i-(/lis utricla L. produces cleistogamous flowers on recurved scapes, 

 at the base of the plant I have not seen them, but have found flowers in 



