Morphology, anatomy and photosynthesis data for two leaf types of Ficus pumila

Plants that display heteroblasty possess conspicuous variations in leaf
morphology between their juvenile and adult phases, with certain species
retaining juvenile-like leaves even in adulthood. Nevertheless, the
ecological advantages of maintaining two or more distinct leaf types in
heteroblastic plants at the adult stage remain unclear. The aim of this
study is to examine the adaptive significance of heteroblastic leaves
sampled from branches with divergent functions (sterile and fertile
branches) of mature Ficus pumila individuals by comparing their
morphological, anatomical, and physiological characteristics. Leaves on
sterile branches (LSs) exhibited a significantly larger specific leaf
area, thinner palisade and spongy tissues, lower chlorophyll contents, and
lower light saturation points than leaves on fertile branches (LFs). These
results demonstrate that LSs are better adapted to low light environments,
while LFs are well equipped to take advantages of high light conditions.
However, both LFs and LSs have a low light compensation point with no
significant difference between them, indicating that they start to
accumulate photosynthetic products under same light conditions.
Interestingly, significant higher net photosynthetic rate was detected in
LFs, showing they have higher photosynthetic capacity. Furthermore, LFs
produced significant more nutrients compared to LSs, which may associate
to their ability of accumulating more photosynthetic products under full
light conditions and higher photosynthetic capacity. Overall, we observed
a pattern of divergence in morphological features of leaves on two
functional branches. Anatomical and physiological features indicate that
LFs have an advantage in varied light conditions, providing amounts of
photosynthetic products to support the sexual reproduction, while LSs
adapt to low light environments. Our findings provide evidence that
heteroblasty facilitates F. pumila to utilize varying light environments,
likely associated with its growth form as a climbing plant. This strategy
allows the plant to allocate resources more effectively and optimize its
overall fitness.

具有异形叶性（heteroblasty）的植物，其幼年期与成年期的叶片形态存在显著差异，部分物种即便进入成年阶段仍保留幼态叶片。然而，异形叶性植物在成年阶段维持两种及以上不同叶片类型的生态学优势仍未明确。本研究以成熟薜荔（Ficus pumila）为研究对象，采集其不同功能分支（不育枝与可育枝）上的异形叶性叶片，通过对比其形态学、解剖学与生理学特征，探究此类叶片的适应意义。实验结果显示，与可育枝叶片（LFs）相比，不育枝叶片（LSs）的比叶面积（specific leaf area）显著更大，栅栏组织与海绵组织更薄，叶绿素含量更低，光饱和点（light saturation points）也更低。上述结果表明，不育枝叶片更适应弱光环境，而可育枝叶片则更适于利用强光条件。不过，两类叶片的光补偿点（light compensation point）均较低且无显著差异，说明二者在相同光照条件下均可启动光合产物积累。值得注意的是，可育枝叶片的净光合速率（net photosynthetic rate）显著更高，表明其光合能力更强。此外，可育枝叶片的养分积累量显著高于不育枝叶片，这可能与其在全光照条件下积累更多光合产物以及具备更高光合能力相关。总体而言，两类功能分支的叶片在形态特征上呈现出分化格局。解剖学与生理学特征表明，可育枝叶片在多变光照环境中更具优势，可通过积累大量光合产物支撑有性生殖（sexual reproduction），而不育枝叶片则适应弱光环境。本研究结果证实，异形叶性有助于薜荔利用不同的光照环境，这可能与其作为攀援植物的生长型密切相关。该策略可帮助植物更高效地分配资源，并优化整体适合度（fitness）。