Inflorescence bracts of fossil and extant Tilia in North America, Europe, and Asia: patterns of morphologic divergence and biogeographic history
Inflorescence bracts of fossil and extant Tilia in North America, Europe, and Asia: patterns of morphologic divergence and biogeographic history
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DOI：
10.1002/j.1537-2197.1994.tb15612.x
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发表时间：
1994-09
影响因子：
3
通讯作者：
S. Manchester
中科院分区：
文献类型：
--
作者：
S. Manchester
现存的椴的扩大花序苞片在北半球有广泛的第三纪化石记录。综述了菊科植物的苞片形态多样性以及花梗与苞片之间的嵌合程度。一种已灭绝的苞片类型，具有圆形轮廓和掌状脉，由化石物种Tilia circularis (Chaney) comb记录。11月产于俄勒冈州渐新世早期，被指定为a型。该属的现存种有细长的苞片，主要有羽状脉，有两种基本形态：B型，花梗仅融合到苞片的极基部，如现存的椴（Tilia endochrysea）。华南地区；和C型具花序梗沿苞片基部三分之一的中部融合，如在大多数现存种中。B型苞片广泛分布于北美西部第三纪（晚始新世至中新世）和欧洲第三纪（早中新世至上新世），而C型苞片仅在亚洲中晚第三纪和欧洲上新世有化石记录。圆茎的苞片，像B型的苞片一样，生在相对较长的茎上，花梗只在最基部融合。化石记录支持以下特征的认识：无柄苞片，花梗贴生于苞片的上表面，羽状苞片脉。椴树广泛分布于北半球，在北美、欧洲和亚洲的落叶阔叶林中有代表性。该属在第三纪化石记录中以花粉、叶和果序的遗迹为代表。虽然它现在的分布主要是温带的，但它属于一个主要是热带的科。木化石（Wheeler, Lee, and Matten, 1987）和花粉化石（Muller, 1976）表明，铁力科及其相关科sterculliaceae， Bombacaceae和Malvaceae的辐射在晚白垩世开始，但铁力属的第一个可靠证据是在大约2000万年后的第三纪。与Tilia相当的花粉最早出现在欧洲古新世（Mai, 1961）、北美始新世（Leffingwell, 1971; Rouse, 1977; Nichols and Ott, 1978）和亚洲（如Kulkova， 1973）。然而，在光镜下，Tilia的花粉与其他属相似，如现存的Craigia和已灭绝的Burretia Mai （Mai, 1961）和Florissantia Knowlton （Manchester, 1992）。因此，基于花粉的报告，没有被电子显微镜记录或被巨型化石证据证实，应该谨慎看待。早在始新世中期，北美洲西部就出现了属于Tilia的叶子
The enlarged inflorescence bract diagnostic of extant Tilia has an extensive Tertiary fossil record in the Northern Hemisphere. Diversity of bract morphology, and the extent of adnation between peduncle and bract, is reviewed for fossil and extant species of Tilia. An extinct type of bract with an orbicular outline and palmate venation is documented by the fossil species Tilia circularis (Chaney) comb. nov. from the early Oligocene of Oregon and is designated Type A. Living species of the genus have elongate bracts with predominately pinnate venation that are borne in two basic configurations: Type B, with the peduncle fused only to the extreme base of the bract lamina, as in extant Tilia endochrysea Hand.-Mzt. of southern China; and Type C with the peduncle fused medially along the basal one-third of the bract lamina, as in most extant species. Bracts of Type B were widely distributed in the Tertiary of western North America (late Eocene to Miocene) and Europe (early Miocene to Pliocene), while those of Type C are known in the fossil condition only from the middle and late Tertiary of Asia and Pliocene of Europe. The bracts of T. circularis, like those of type B, are borne on relatively long stalks and have the peduncle fused only at the extreme base. The fossil record supports recognition of the following characters as apomorphic in Tilia bract evolution: bracts sessile, peduncle adnate to the upper surface of the bract, and pinnate bract venation. Tilia is distributed widely in the Northern Hemisphere with representatives in the deciduous hardwood forests in North America, Europe, and Asia. The genus is well represented in the Tertiary fossil record by pollen, leaf, and infructescence remains. Although chiefly temperate in its present-day distribution, Tilia belongs to a family that is mainly tropical today. The radiation of Tiliaceae and related families Sterculiaceae, Bombacaceae, and Malvaceae was underway by the Late Cretaceous, as indicated by fossil wood (Wheeler, Lee, and Matten, 1987) and pollen (Muller, 1976), but the first reliable evidence of the genus Tilia is about 20 million years later in the Tertiary. Pollen closely comparable to that of Tilia first appears in the Paleocene of Europe (Mai, 1961) and in the Eocene of North America (Leffingwell, 1971; Rouse, 1977; Nichols and Ott, 1978) and Asia (e.g., Kulkova, 1973). By light microscopy, however, pollen of Tilia is similar to that of other genera such as extant Craigia and the extinct genera Burretia Mai (Mai, 1961) and Florissantia Knowlton (Manchester, 1992). Therefore, reports based upon pollen that are not documented by electron microscopy or corroborated by megafossil evidence should be viewed with caution. Leaves attributed to Tilia occur as early as the middle Eocene in western North America