452 Floristik und Systematik der Phanerogamen. 



is an abscission-layer of very thin-walled cells, lying between masses 

 of cells with thick gelatinous walls. The top of the fruit is able to 

 resist considerable pressure from within the fruit, while the middle 

 and lower parts develop pressure, whenever they can absorb enough 

 water; the line of mechanical weakness is the abscission layer, and 

 when the fruit breaks at the base, the compressive action of the 

 resistant upper half of the fruit, assisted by the conical shape of 

 the seed, causes the forcible propulsion of the latter. The greater 

 part of the seed is covered by a gelatinous layer of much-elongated 

 cells, attached obliquely or at right angles to cells of the inner 

 sclerotic layer. The seeds germinate on anything; the cotyledons 

 are represented only by a slight notch at the lower end of the 

 embryo; the root is negatively phototactic, does not appear very 

 sensitive to contact, and grows on until its further growth is oppo- 

 sed by some obstacle. It then forms a thick holdfast of growing 

 parenchymatous cells, into which the food-material from the coty- 

 ledonary end is transferred, so that the latter shrinks. The haustorium 

 then penetrates the brauch of the host, the cells at the tip spreading 

 out and forming Strands of infecting-cells, which ultimately effect 

 a direct attachment with the young wood-cells of the host and 

 differentiate into tracheids, etc. The main part of the haustorium 

 increases in size and forms a mass of perennial parasitic cells in 

 the cortex of the host; this mass presently differentiates into con- 

 ducting and parenchymatous tissues and buds form, which develop 

 into branches, growing out through the bark into the air; they become 

 green and exhibit a marked xerophytic structure in correspondence 

 with the conditions of life in surnmer. There is a perfect con- 

 nection between the xylem of parasite and host, while the author 

 was unable to find similar relations in the case of the phloem, but 

 osmotic transfer is thought to obtain. Goebel's view of the haus- 

 toria as organs „sui generis" is discussed and it is shown that in 

 Arceiäliobium the haustorium is certainly a modified root. 



F. E. Fritsch. 



Sampaio, G., Contribu9ion para o estudo da flora portu- 

 gueza. — Epilobiaceae. (Bol. de Soc. Brot. XXI. 1906.) 



Description de toutes les especes de cette famille r^colt^es en 

 Portugal et appartenant aux genres Epilohium (9), Oenothera (4), 

 Ludwigia (1), Circaea (1). Du genre Epilohium l'auteur cite 4 

 hybrides. 



La distribution g^ographique est indiqude et cette dtude comme 

 Celle des Romnlea est terminde par une clef dichotomique pour la 

 d^termination des especes. J. Henriques. 



Sampaio, G., Contribu9ion para o estudo da flora portu- 

 gueza. Genere Romiilea. (Bol. de Soc. Brot. XXI. 1906.) 



Etüde des espfeces de Romnlea rdcoltdes en Portugal. L'auteur 

 apres la description generale des organes de ces plantes les dispose 

 en deux sections d'aprfes la longeur relative du tube du p(^rianthe 

 — Brevituhiferae et Longituhiferae — chacune divisde en deux 

 groupes d'aprfes les caractferes de la bract^e sup6rieure de la spathe. 

 Cinq espfeces sont ddcrites: R. Clusiana, Bulbocodium, Coliimnae, 

 ramiflora et tenella, espfece nouvelle se rapprochant du R. ramiflora. 



J. Henriques. 



