74 LAWSON — MONOGRAPH OF ERICACE^. 



Art. VIII. — Monograph of Eric ace je of the Dominion of 

 Canada and adjacent parts of British America. 

 By George Lawson, Ph. D., Ll. D., Professor of 

 Chemistry, Dalhousie College, Halifax, iV. S, 



{Read April 10, 1871.) 



The order Ericace^ embraces plants which for beauty are not 

 excelled by any that are known to Science, and although their 

 affinities are clear and the order is a jDerfectly natural and well 

 defined one, yet its members are so polymorphous that there is not 

 only great variety within its limits in habit and foliage, but also in 

 the structure and number of parts of the flower, and in the real 

 character as well as outward aspect of the fruit. Most of these 

 plants are shrubs, some tall and erect, others dwarf and procum- 

 bent ; some have deciduous leaves, others are broad-leaved ever- 

 greens, the duration of the leaves often diiFering in species of the 

 same genus ; some are humble herbaceous plants with a rosette of 

 evergreen radical leaves and annual flower-stalks ; and some are 

 scaly leafless parasites. In the Whortleberry group the calyx-tube 

 is adherent to the ovary, forming a succulent fruit. In the Bhodo- 

 dendron and Heath Group, there is no adhesion, and the fruit is dry 

 and dehiscent, except in Arctostaphyllos, which has a succulent 

 fruit. In the Pyrola group the corolla is polypetalous ; in most of 

 the other groups it is gamopetalous and usually but not always 

 regular, the petaloid divisions of equal size. In this order we have 

 the connecting link that bridges over the gap between polypetalous 

 and gamopetalous exogens, for it includes some plants that must be 

 referred to the one division, and some that as surely belong to the 

 other, thus showing that the distinction is neither an absolute nor a 

 natural one when applied to orders. 



The largest and most showy plants of the order belong to the 

 Khododendron tribe, of which many new species have been dis- 

 covered and introduced to gardens of late years. M. Maximowicz 

 has re-arranged the genera of this tribe in accordance with the 

 growing opinions of botanists that some of the old generic distinc- 



