54 



P. R. WYCHERLEY 



7.3. Cytological Observations 



Seminiferous D. cespitosa has chromosome numbers of : 2n = 26 (Lawrence, 1945 j, 

 2n = 28 (Avdulow, 1931 ; Nielson & Humphrey, 1937 ; and Hagerup, 1939). Seminiferous 

 D. alpina 2n = 26 (Nygren, 1949). Slightly or partly viviparous D. alpina 2n = 39 

 (Flovik), strongly or fully viviparous D. alpina 2n = 41, 49, 52 and 56 (Flovik, 1938; 

 Hagerup, 1939; and Nygren, 1949). Nygren traced a series of increasing vivipary with 

 polyploidy. 



In the present work, various root squash techniques were unsuccessfully attempted" 

 Therefore root-tips were sectioned and the chromosomes in metaphase plates counted by 

 means of a camera lucida (total magnification X 1,000). Chromosomes were about 

 5 fji long. In sectioned material there is no certainty that plates are complete or that 

 long chromosomes have not been cut into parts. In practice the best plates were counted 

 and the modal number taken. The numbers in Table 5 are given as approximate and 

 not as a critical study. But they are adequate to demonstrate that cytology is a poor 

 key to the classification of the viviparous Deschampsiae. 



Table 5 



Approximate Diploid Chromosome Numbers of Deschampsiae 



Location 



var. pseudalpina 



" intermediate " 



D. alpina 



West Mayo 



44,44.47,47,49 



34,37 



34 



North Wales 



37 







Lake District 



32 







Grampians 



(31-32), 41 





38 



Western Is'es 



36 



39 



36 



The numbers are erratic. The morphological characters are also somewhat randomly 

 arranged if awn-type is used as a key. This suggests that there is considerable variation 

 due to occasional sexual reproduction. In D. alpina especially, good stamens are common 

 and not infrequently well-formed pistils are found. 



7.4. The employment of the names Deschampsia alpina (L.) Roem. & Schult. and Deschampsia 

 cespitosa var. pseudalpina (Syme) Druce 



All facets of the subject, historical, morphological and cytological, show how weak 

 is the distinction between the two forms. All forms cannot be brought within D. alpina 

 (L.) R. & S., unless absence of an awn due to metamorphosis is counted as insertion above 

 the middle of the third glume. This is supported by the transition series and that, in 

 this series, D. alpina stands closer to seminiferous D. caespitosa than the var. pseudalpina, 

 which is allegedly a segregate of the latter. 



The different ranges argue for their retention and fuller knowledge may be lost 

 by failing to distinguish them, especially as these observations are confined to the British 

 Isles. 



Two forms are recognized : Deschampsia alpina (L.) Roem. & Schult. in which 

 the awn is inserted about the middle or upper part of the dorsal rib of the third glume 

 (lemma of the lowest floret), and D. cespitosa var. pseudalpina (Syme) Druce in which 

 proliferous metamorphosis prevents the distinction of a separated awn. There are 

 intermediate forms between them, and spikclcts of the same panicle may not all fall 

 into one category. 



