g6 The Flora of Glaiitorgan. 



859. eriophorus, Roth. Woolly-headed Thistle. 

 Local. Abundant. Native. Viatical, pascual. 



Very wide spread and often very abundant on the liassic clays 

 of the Vale of Glamorgan. Newton Nottage ; between Neath and 

 Pyle. L.W. D.Mat. 



860. palustris, Willd. Marsh-Thistle. Ysgallen y gors. 

 Common. Abundant. Native. Pratal, inundatal, etc. 



Often with white flowers. 



861. tuberosus, Roth. Tuberous Thistle. 



Rare. Abundant. Native. Pascual, littoral. 



In some respects the most interesting plant in Glamorgan. 

 Between St. Donats and Dunraven. T. Westcombe. Phyt. 1844. 

 p. 780. Referred, however, by T. B. Flower and H. C. Watson to 

 C. Woodwardii. Phyt. 1852. p. 519. Riddelsdell questioned the 

 accuracy of this conclusion, and suggested it might be a form of 

 C. acaulis. Bot. Exch. Club Report. 1904. />. 25. In his Flora of 

 Glam. p.2i9, however, he says " apparently " C. tuberosus ; and in 

 Bot. Exch. Club Report, 1907, definitely C. tuberosus. Not having 

 seen a specimen of the Wiltshire plant, I sent fresh material to 

 Mr. A. Bennett, in 1905, who reported " Not C. tuberosus," but have 

 " little doubt " it is Watson's C. Woodwardii. It does not accord 

 at all well, however, with a specimen of C. Woodwardii in the British 

 Museum. 



It still remains necessary to consult type plants of these two 

 forms, but in the meantime, the balance of evidence is in favour of 

 the conclusion that our plant is C. tuberosus and not C. Woodwardii. 

 I transplanted a specimen into my garden at Penarth in 1905, the 

 soil being similar to that of its native habitat. I collected seeds 

 from Nash plants in 1905 and 1906, and raised plants in 1906 and 

 1907. These proved to be perennials uniformly true to type, flowering 

 in the second and subsequent year. C. acaulis may flower in the 

 first year. I grew the reputed parents on each side of the colonies 

 of C. tuberosus, only to be astonished that any one should imagine 

 that these plants could be related to each other in this manner. 

 Moreover, not only does C. tuberosus grow in its native habitat at 

 a distance from C. pratensis — as Riddelsdell has already stated — but 

 the flowering period of C. pratensis is over long before that of 

 C. acaulis begins, so that I have not been able to secure pollen to 

 attempt to make the cross artificially. The main root is distinctly 

 tuberous (like a stout carrot) in the first and especially in the second 

 year, and the primary stem terminates its existence in the second 

 year by producing the main inflorescence. After the seeds have been 

 ripened, the primary stem dies down, and the buds axillary to the 

 basal leaves grow out to form short ascending branches. New roots 

 form on the under side of these branches, and develop into smaller 

 fusiform tubers, the old one becoming hollow and soon reduced to 

 a skeleton framework of vascular bundles. In consequence of similar 

 growths year after year, the old stems appear to creep a little, but 

 they never develop long rhizomes such as are characteristic of 



