Foliage and fruits of early poplars (Salicaceae: Populus) from the eocene of Utah, Colorado, and Wyoming
Foliage and fruits of early poplars (Salicaceae: Populus) from the eocene of Utah, Colorado, and Wyoming
复制标题
DOI：
10.1086/503918
复制
发表时间：
2006-07-01
影响因子：
2.3
通讯作者：
Handley, Bruce
中科院分区：
文献类型：
--
作者：
Manchester, Steven R.;Judd, Walter S.;Handley, Bruce
本文通过对犹他州东部和科罗拉多州西部绿河组中始新世早期降落伞溪段大量标本的分析，发现了一种杨树新种，并与另外两种当代杨树进行了比较。一根既长有叶子又有果实的罕见树枝作为罗塞塔石碑，连接了以前只从分散的器官中知道的营养和生殖结构。结果和叶片特征区分了胡杨（Populus tidwellii sp. n.）和胡杨（Populus cinnamomoides (Lesquereux) MacGinitie）（在WY绿河站的标本上进行了分型），前者的分离叶以前被归为后者。此外，新的果实和叶片数据证实，降落伞溪植物区系中存在两个不同的同域杨种（P. tidwellii和Populus wilmattae）。这些物种，连同假柳和柳，提供了我们最早的多样化水杨科的记录。P. tidwellii的一个有趣的特征是花序是顶生的，而不是现存的杨树品种，其中柳絮是腋生的，并在前一个季节的木材上生长。此外，果序在其基部附近有侧向分枝，区别于该属现存种的简单总状花序。
A new species of poplar is recognized based on abundant specimens from the early Middle Eocene Parachute Creek Member of the Green River Formation in eastern Utah and western Colorado and compared with two other contemporary species. A rare twig bearing both leaves and fruits serves as a Rosetta stone, linking the vegetative and reproductive structures that formerly were only known from dispersed organs. Fruit and foliage characters distinguish Populus tidwellii sp. n. from Populus cinnamomoides ( Lesquereux) MacGinitie ( typified on specimens from Green River Station, WY), to which the isolated leaves had formerly been attributed. In addition, new data from fruits and foliage confirm that there were two distinct sympatric species of Populus in the Parachute Creek flora ( P. tidwellii and Populus wilmattae). These species, together with Pseudosalix and Salix, provide our earliest record of diverse Salicaceae. An interesting feature of P. tidwellii is that the inflorescence is terminal in contrast to extant species of Populus, in which the catkins are axillary and borne on wood of the previous season. In addition, the infructescence shows lateral branching near its base, distinguishing it from the simple racemes of extant species of the genus.