PARRY CEANOTHUS. 1 65 



from the old wood. It is only when the fruiting process is well ad- 

 vanced, that the summer shoots set to work to prepare flower buds for 

 the next season, occasionally however, tempted by an early autumnal 

 rain or favorable conditions of growth, to push out premature flower 

 buds, which, in their starved aspect, show that they are out of season, 

 associated as they are, with fully developed fruit of the same year. 



CHARACTERS ON WHICH SPECIES AND GROUPS CAN BE MOST 

 SATISFACTORILY DEFINED. 



Before proceeding to an enumeration of the species here recognized 

 in the accompanying synoptical list, it seems proper to dwell briefly on 

 some of the most reliable characters, especially such as are brought to 

 view in field observations, which afford the best means for defining spe- 

 cies and arranging them in natural groups. And first, the ramification 

 of Ceanothus offers some distinctive features. Thus, while the thrifty- 

 growing species, such as C. tJiyrsifiorus, C. arboreus, C. integerrimus, 

 and several others exhibit the usual prolonged growth and flexible 

 branches, usually more or less angular when young, and destitute of 

 spines; others, subjected to more arid conditions of soil and climate, 

 show a disposition to branch at right angles to the main axis, which 

 branches, failing to secure sufficient nourishment for prolonged growth, 

 terminate abruptly in stiff spines, which, interlocking, form the thickets 

 popularly known as chaparral. These contrasted characters, while 

 clearly noticeable in certain groups, are not always sufficiently constant 

 to define their limits. 



Again, an important character, not always apparent in herbarium 

 specimens, is the relative persistence of the foliage; this, there are in- 

 cluded in this genus, species with annually deciduous leaves, showing 

 naked winter branches, while others are strictly evergreen, retaining 

 their leaves indefinitely — while there is still a larger intermediate class, 

 including most of the Pacific coast species, in which the leaves persist 

 for at least two seasons, and never show purely naked stems on the 

 upper branches. It is quite possible that these characters would accu- 

 rately define three very distinct natural divisions, as will be partly in- 

 dicated in the succeeding list. 



Still farther the venation and pubescence of the leaves offers good 

 distinguishing marks, and these being equally available to the closet 

 and field botanist, have been largely relied on by the former to limit 

 groups, and may, no doubt, be used to advantage, when properly com- 

 bined and qualified by other constant characters, so that species other- 

 wise widely diverse, may not be brought together in unnatural, artificial 



