514 Royal Irish Academy. 



grasses were so unlike in general appearance to any of the other 

 Po(e, and possessed such strong marks of specific distinction, that he 

 considered them entitled to rank as distinct species. 1 . Poa secti- 

 palea (Parnell). This plant differs from Port j9r«^eHszs, the only spe- 

 cies it can well be confounded with, in the branches of the panicle 

 being stouter, more erect and rigid ; the spikelets larger. Outer 

 palea seven- or nine-ribbed, seven of the ribs being very distinctly 

 marked ; inner palea one-third shorter than the outer, and invariably 

 divided to the very base, whereas in Poa pratensis the inner palea 

 has never more nor less than five ribs, and the inner very little shorter 

 than the outer, and always entire. Found growing in sandy situ- 

 ations between Crammond and Queensferry. — 2. Poa polpioda (Par- 

 nell). This species differs from Poa compressa in the florets not 

 being ribbed at the base ; outer palea five-ribbed. Joints from eight 

 to nine in number, the uppermost joint situated but a short distance 

 from the panicle ; whereas in Poa compressa the florets are very di- 

 stinctly ribbed, suspending the calyx by their silky fibres. Outer 

 palea three-ribbed. Joints seldom exceeding four in number. — 3. Poa 

 nemoralis montana, Koch. Inflorescence simple, panicled, occasion- 

 ally racemed. Panicle erect, narrow and slender ; the branches 

 erect, long and slender, bearing few spikelets. Spikelets lanceolate- 

 ovate, of two or three awnless florets. Calyx of two unequal, acute 

 glumes, three-ribbed. Florets not in the slightest degree webbed. 

 Outer palea five-ribbed, the dorsal and marginal ribs slightly hairy. 

 The whole plant is of a glaucous hue. This grass was first obtained 

 by Dr. Greville, who, in the year 1833, gathered several specimens 

 on Ben Lawers ; since then it has been found in many parts of the 

 Highlands, but has hitherto been considered as a glaucous variety of 

 P, nemoralis. 



These grasses are figured in Dr. Parnell's work on the Scottish 

 Grasses, now in the press, in which he has given 130 figures, with 

 minute descriptions. 



ROYAL IRISH ACADEMY. 



Jan. 25, 1841. — His Grace the Archbishop of Dublin communi- 

 cated some observations " On the Leafing of Plants." 



It is well known that there is a diversity in the times of leafing and 

 shedding in individual trees of the same species ; e. g. hawthorn, syca- 

 more, horse-chestnut, beech, &c., sometimes as much as a fortnight; 

 and the earliest in leaf are also the earliest shed, the same individuals 

 keeping their time every year. Hence the question, whether this di- 

 versity arises from the "separable accidents" of soil, situation, &c., 

 or whether from " inseparable accidents," which constitute what 

 physiologists call varieties ? 



An experiment was tried by grafting an early hawthorn on a late, 

 and vice versd. The scions kept their times (about a fortnight's dif- 

 ference) as if on their own stocks, thus proving that it was a case 

 of " seedling variety." 



Many other such varieties are known, not only of apples, peaches, 

 &c., but of wild trees also, differing in shape of leaf, form of growth, 

 colour and size of fruit, &c., and also time of ripening. It was there- 



