五月下旬至六月初,是杨树、榆树种子的成熟时期。杨树和榆树是我区造林的主要树种,种源也比较丰富,抓住时机把种子采到手,对加快造林绿化步伐和增加群众收入,都具有重要作用。杨树雌雄异株,母树的果实为穗状蒴果,种子细小,藏于蒴果内的绒絮之间。蒴果成熟后容易自行开裂,使种子随风飞散,因此,需要事先调查种源、选好母树,并注意观察果穗变化情况,以免错过适宜的采种时机。采集杨树种子有在地面扫集绒絮(亦称飞花)或在树上采摘果穗两种办法。城市里的行道树或地面杂草较 Late May to early June, poplar, elm seeds mature period. Poplar and elm trees are the main tree species for afforestation in our area, and their provenances are also rich. Seizing the opportunity to seize the seeds will play an important role in accelerating the afforestation and increasing the masses’ income. Poplar dioecious, the fruit of the female tree is a spiculate capsule, the seed is small, hidden in the velvet between the capsule. Capsules are easy to self-rupture when mature, so seeds need to be scattered with the wind. Therefore, it is necessary to investigate the provenance in advance and choose the mother tree carefully. Observe the change of the ear, so as not to miss the appropriate time for seed collection. Poplar seeds collected on the ground sweeping flocculent (also known as fly) or picking fruit in the tree two ways. Street trees or ground weeds in the city