Clonal plants present an interesting example of division of labour among their ramets. Here we elaborated on hydraulic structure in respect to the division of labour among ramets in Arundo donax, a perennial clonal reed. Mature clones have three shoot types: (1) large mostly flowering; (2) medium mostly vegetative and (3) small vegetative. The shoots grow from buds initiating in the upper side of underground rhizomes, and the shoot growth is primary with vasculature produced from the procambium. We tested whether the number of vascular strands in a shoot has a fixed developmental programme or follows a flexible developmental pattern, and we found that the number of vascular strands strongly differs between shoot types. Large shoots on average have 560 vascular strands with both the widest vessels and significantly highest hydraulic conductivity. Medium ones and small shoots have 409 and 102 on average, respectively, with narrower vessels and with low conductivity. Thus, the shoot apices have three alternative developmental programmes. Apparently, a clone is built of functionally different modular units that enable Arundo donax to maximize its potential in a heterogeneous environment. Although the smaller culms do not contribute directly to the sexual reproduction of the clone, under stress their safer hydraulic system offers them a better chance of survival.

中文翻译：

---

预先确定的水力结构使无性芦苇Arundo donax（Poaceae）的茎杆分工

克隆植物是分株之间分工的有趣例子。在这里，我们详细介绍了Arundo donax分株间分工的水力结构，多年生克隆芦苇。成熟的无性系有三种芽类型：（1）大，多数开花。（2）中型多数为植物性营养，（3）小型为植物性。芽是从地下根茎上端开始的芽生长而来的，芽的生长主要是由菌根产生的脉管系统产生的。我们测试了芽中维管束的数量是否具有固定的发育程序或遵循灵活的发育模式，并且我们发现，芽类型之间的维管束的数量存在很大差异。大枝条平均有560根血管，血管最宽，水力传导率最高。中，小枝条平均分别具有409和102个，具有较窄的容器和低电导率。因此，芽尖具有三个替代的发育方案。Arundo donax可在异构环境中最大程度地发挥其潜力。尽管较小的茎杆并不能直接促进克隆的有性繁殖，但在压力下它们较安全的液压系统为它们提供了更好的生存机会。