148 



HARDWICKKS SCIENCE-GOSSIP. 



very closely, ensuring a compact barrier against the 

 intrusion of insects from without ; and the two sets 

 of sepals are placed alternately and are well provided 

 with hairs on their margins. 



The ray florets, which present an attractive circle 

 of bright yellow, are unisexual, possessing the female 

 organ only ; but this is perfect, and in due time 

 receives the pollen which fertilises the seed, the latter 

 being contained in an achene of semicircular shape at 

 the foot of each floret. 



The blossoms are in three parts. Within these is 

 a barren pistil ; next, and surrounding it, five stamens 

 joined at the upper part so as to form a tube ; and, 

 outside all, a monopetalous five-lobed corolla. The 



Fig. 58. — Part section of complete flower. 



barren pistil ends in a blunt stigma, of a somewhat 

 pyramidal shape, covered with short spines. Its 

 office appears to be to raise the pollen by brushing it 

 off the anthers. 



The order in which the important organs come to 

 maturity is as follows : — 1st. The anthers discover 

 themselves just above the corolla, hitherto closed. 

 2nd. The barren stigma is observed gradually thrusting 

 itself upwards till it stands displayed. 3rd. The fertile 

 pistil of each ray-floret shows slightly above the level 

 of the disc and then divides at the top ; previously it 

 was concealed between its particular floret and the 

 nearest outside blossom of the disc. To sum up, the 

 disc blossoms mature in regular order, beginning from 

 the outside, and when one or more rows are matured, 

 the fertile pistils become faintly visible. Cross- 

 fertilisation is secured by the above arrangement, 

 because, when the first pollen is available, there is no 

 fertile pistil whereon it can be deposited. An insect, 

 therefore, after brushing off pollen, will probably 

 carry it to some other flower, possibly on another 

 plant, where the fertile pistil has appeared. 



I am inclined to believe that fertilisation is largely 

 carried on by very small insects that crawl bodily into 

 each corolla in search of nectar ; and, inasmuch as 

 they first attack the corollas on the outside of the disc, 

 they are likely to rub their bodies against the fertile 

 pistils. I am confirmed in this opinion by the fact, 

 that the fertile pistils barely disclose themselves above 

 the disc, so that a large insect would rarely if ever 

 touch them. I observed a minute beetle about T ' 3 of 

 an inch long to be a constant visitor, and I have 

 frequently seen it almost bury itself down a corolla. 



No doubt its action had the effect of pushing down 

 the anthers and thus helping the stigma to rise, 

 I think that, if it were not for these insects and 

 others acting in a similar manner, fertilisation would 

 never take place. Again, the formation of the entire 

 flower is in favour of the supposition, that small insects 

 alone are concerned in the important process ; for, if 

 the duty had to be performed by large ones, it is most 

 likely that each blossom would have been a perfect 

 flower, and then a large insect when thrusting its 

 proboscis down the corolla would, at the same time, 

 press against a fertile pistil. The habit, too, of the 

 complete flower closing up at night points in the 

 same direction ; for many large moths fly about then, 

 and their attentions, far from being serviceable, might 

 be positively injurious, as they would, but for this, 

 remove pollen without placing it where required. 



The barren stigma is a singular feature. It is an 

 instance of how a part may be made to subserve 

 a purpose for which it was not originally intended 

 and modified to suit the surroundings. Without the 

 assistance of this barren stigma, it is doubtful whether 

 pollen would ever be separated from the minute 

 anthers and raised to a position to be available for 

 visiting insects. 



The figure represents a part section of a complete 

 flower, magnified about four times, with only three 

 blossoms a ray floret and a bract left standing, by 

 which some idea may be gained of the method 

 of fertilisation. 



224 Cambenvcll New Road, S.E. 



NOTES ON TRIFOLIUM STELLATUM. 



AMONG the improvements of the last edition of 

 the ' London Catalogue of British Plants ' is 

 the inclusion of such of our non-native plants, "as 

 are now thoroughly established and look quite wild." 

 Some of these formerly denominated as " casuals " are 

 thus very properly admitted to our Flora. Mentioning 

 the starry-headed trefoil to a botanist at Kew as 

 occurring at Shoreham, a friend was recently told 

 that it was formerly to be found there ; but had long 

 since disappeared. This, I am glad to say, is by no 

 means the case , for on the low line of shingle near 

 Shoreham Harbour this lovely plant exists in pro- 

 fusion. As confined to Sussex, and as having been 

 established in its present locality for nearly a century, 

 a few observations on it may be offered. How it 

 gained its footing on this point of the south coast, and 

 there only, is unknown. The seeds may have been 

 scattered from some wreck, or imported in some of 

 the curious modes of plant distribution described by 

 Darwin. Gerard appears to have been acquainted 

 with it in the sixteenth century ; for, speaking of 

 Bauhm's Trifolium sttflatiim, he says "for distinction's 

 sake, I adde hirsutum, calling it Trifol, stcllatum 

 hirsutum" and his description of it is so quaint and 



