Abstract Annual growth rings are absent in many long-lived grassland geoxyles. Thus, estimates of age for individuals are largely based on non-benchmarked assessments by experienced botanists. We wished to obtain a more precise estimate of age from the xylopodia of four geoxylic taxa (i.e. Berkheya insignis, Callilepis laureola, Protea simplex and Tephrosia kraussiana) growing in a Pondoland grassland, using both the gas proportional counting and Accelerated Mass Spectroscopy radiocarbon dating techniques. Plants sampled in 2008 fell within modern concentrations of carbon 14; therefore, radiocarbon dating generally yielded two ages for each plant, an older age (range: 45–51 years, mean=49, CV=3.6%) corresponding with the nuclear testing period, and a younger age (range: 10–29 years, mean=18, CV=35%), corresponding to the period after the Partial Nuclear Test Ban Treaty. Hence the older ages are much less variable than the younger ages. All plants had the older age estimate, and all but two had the younger age estimate. In addition, two plants each, had two similar older age estimates. P. simplex plants were 16, 24, 27 and 29, or 45, 46–49, 47 and 49 years, T. kraussiana 13, 15 and 16, or 50 and two of 51 years, C. laureola 12, 15 and 21, or 49–50 and two of 50 years and B. insignis were 10, or 49, 50 and 51 years old. Growth rings were not visible with the naked eye. However, using stereomicroscopy, ring-like patterns were visible to some extent at 7X magnification for B. insignis, P. simplex and T. kraussiana, but not C. laureola. Counts of these structures were much lower than the younger 14C dates, and hence are unlikely to be annual rings. Despite the ambiguity of multiple ages, these estimates are a useful starting point or benchmark for future empirical investigations of age for forbs with no clear annual rings. Most studies have used radiocarbon dating to estimate the age of woody tree stem tissue, whereas this study is one of few to measure the age of below-ground modern tissues of South African forbs. Suggestions for further refinement during collection and processing of geophytic sample material are made based on lessons learned from this investigation.

中文翻译：

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没有环时的碳 14 年代测定：Pondoland 草原地质的四岁和经验教训

摘要 许多长寿的草原土生土长寿命年轮不存在。因此，对个体年龄的估计主要基于经验丰富的植物学家的非基准评估。我们希望使用气体比例计数和加速质谱法放射性碳测年技术，从生长在 Pondoland 草原的四种地质类群（即 Berkheya insignis、Callilepis laureola、Protea simplex 和 Tephrosia kraussiana）的木足获得更精确的年龄估计. 2008 年采样的植物属于现代碳 14 浓度；因此，放射性碳测年通常为每个工厂产生两个年龄，一个年龄较大（范围：45-51 岁，平均值 = 49，CV = 3.6%）对应于核试验期，和一个较年轻的年龄（范围：10-29 岁） , 平均值=18, CV=35%), 对应于《部分禁止核试验条约》之后的时期。因此，年龄较大的年龄比年轻年龄的变化要小得多。所有植物的年龄估计值都较大，除两株外，所有植物的年龄估计值都较小。此外，每两株植物都有两个相似的年龄估计值。P. simplex 植物为 16、24、27 和 29 年，或 45、46-49、47 和 49 年，T. kraussiana 13、15 和 16 年，或 50 年和 51 年中的两个，C. laureola 12、15 和 21 年，或 49-50 岁，50 岁和 B. insignis 中的两个是 10 岁，或 49、50 和 51 岁。肉眼看不到生长轮。然而，使用立体显微镜，B. insignis、P. simplex 和 T. kraussiana 在 7X 放大倍数下在某种程度上可以看到环状图案，但 C. laureola 则看不到。这些结构的数量远低于更年轻的 14C 日期，因此不太可能是年轮。尽管多个年龄存在歧义，但这些估计是未来对没有明确年轮的杂草进行年龄实证研究的有用起点或基准。大多数研究使用放射性碳测年法来估计木本树茎组织的年龄，而这项研究是为数不多的测量南非杂草地下现代组织年龄的研究之一。根据从这次调查中吸取的经验教训，提出了在地球植物样本材料的收集和处理过程中进一步细化的建议。而这项研究是为数不多的测量南非杂草地下现代组织年龄的研究之一。根据从这次调查中吸取的经验教训，提出了在地球植物样本材料的收集和处理过程中进一步细化的建议。而这项研究是为数不多的测量南非杂草地下现代组织年龄的研究之一。根据从这次调查中吸取的经验教训，提出了在地球植物样本材料的收集和处理过程中进一步细化的建议。