central segment obovate, base cuneate, midrib elongate to tip, apex acute to sub truncate, usually shallowly 3-lobed;

1、

adaxial surface green, glabrous, midrib and lateral veins raised abaxially, flat adaxially;

正面绿色，无毛，中脉和侧脉背面突起，正面平；

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2、

adaxial surface glabrous; midrib raised abaxially, concave adaxially;

正面无毛背面中脉突起，凹的正面；

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3、

abaxial surface with hairs only on the midrib and lateral veins;

先端渐尖或锐尖的背面只在中脉和侧脉上具毛；

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4、

adaxial surface green, glabrous when mature, midrib raised abaxially, grooved adaxially;

正面绿色，成熟时无毛，背面的中脉突起，正面具槽；

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5、

adaxial surface deep green; midrib slightly raised abaxially, slightly grooved adaxially;

中脉稍突起背面，正面稍微地在上面具槽；

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6、

apex acute; abaxial surface at first sparsely strigose, later sometimes coarsely strigose on midrib only;

先端锐尖有时晚，最初背面疏生糙伏毛具糙伏毛在仅在中脉上；

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7、

adaxial surface green, glabrous, midrib plane or slightly grooved adaxially;

正面绿色，无毛，中脉平或者稍微正面具槽；

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8、

abaxial surface pale green, midrib with verrucose spots;

背面苍绿色，中脉具瘤状的斑点；

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9、

adaxial surface glabrous except for groove of midrib towards base;

正面无毛除了中脉凹槽向基部的；

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10、

abaxial surface pale, only lower half of midrib densely fine branched-hairy;

背面浅，仅下半部中脉浓密细分枝的毛；

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11、

adaxial surface deep green, slightly floccose when young, glabrous when mature, midrib prominent abaxially, grooved adaxially;

幼时的正面深绿色，稍被丛卷毛，成熟时无毛，中脉背面突起，正面具槽；

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12、

adaxial surface green, smooth, glabrous or with vestiges of juvenile hairs on the midrib;

正面绿色，平滑，无毛或者具幼时毛的痕迹在中脉上的；

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13、

leaf blades cauline, narrowly to broadly linear, midrib usually broad, white;

叶片茎生，狭到宽线形，通常宽，白色；

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14、

abaxial surface glabrous except sometimes for densely woolly midrib;

背面无毛，除有时中脉的密被绵状毛；

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15、

sepals 4, biseriate, unequal, often outer ones narrower, membranous or papery, entire or denticulate, with midrib and branching veinlets;

萼片4，双列，不等长，通常外轮狭窄，膜质或纸质，全缘或具细牙齿，具中脉和分枝细脉；

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16、

changes in nicotine conversion rate in lamina and midrib of burley tobacco and between from different stalk positions

白肋烟叶片、主脉及不同叶位间烟碱转化率的差异

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17、

abaxial surface persistently pale white-brown to rufous tomentose, sometimes only on the midrib, hairs branched;

被绒毛的浅白色的棕色到红棕色的背面持续，有时只在中脉，毛分枝；

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18、

abaxial surface scales dense, yellow to brown, large, unequal or all similar, often without hairs, sometimes pubescent along midrib;

背面鳞片紧密，黄的到棕色，大，不等长或全部相似，通常没有毛，有时沿中脉具短柔毛的；

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19、

abaxial surface persistently tomentose towards base, especially near prominent midrib, hairs stellate;

背面持续被绒毛向基部，特别近突出，星状的毛；

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20、

abaxial surface floccose or not on midrib, rarely with a sparse white stellate indumentum (r. asterochnoum);

由中脉，很少具开出的不背面被丛卷毛或一稀白色毛被（R。asterochnoum）；

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