Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

Phenotypic differences in sun and shade leaves

of Monstera deliciosa (Araceae)

Valeria Díaz-Valverde1; https://orcid.org/0009-0007-7335-9216

Gerardo Avalos*1,2; https://orcid.org/0000-0003-2663-4565

Julián Quesada-Fonseca1

1. Escuela de Biología, Universidad de Costa Rica, 11501-2060 San Pedro, San José, Costa Rica; Valeria.diazvalverde@ucr.

ac.cr; gerardo.avalos@ucr.ac.cr; julian.quesadafonseca@ucr.ac.cr

2. The School for Field Studies, Center for Sustainable Development Studies, 100 Cummings Center, Suite 534G, Beverly,

Massachusetts 01915, USA; gavalos@fieldstudies.org (*Correspondence)

Received 22-I-2024. Corrected 04-IV-2025. Accepted 09-VI-2025.

ABSTRACT

Introduction: Leaves are among the most plastic organs in plants, and their structure, while shaped by phy-

logeny, can show considerable phenotypic plasticity within a species in response to environmental gradients.

Monstera deliciosa, a tropical hemiepiphytic vine known for high leaf heteroblasty, adapts to diverse light condi-

tions. This makes leaf structure a useful proxy for assessing whole-plant resource allocation strategies and adapta-

tions to environmental changes.

Objective: To measure the morphological and structural differences in sun and shade leaves using nine leaf traits

(petiole length, leaf width and length, effective leaf area, fenestrated area, leaf perimeter, lobulation ratio, stomatal

density, and specific leaf area -SLA-).

Methods: We selected 20 widely separated M. deliciosa plants on the University of Costa Rica campus in 2022,

positioned in contrasting sun and shade conditions, and measured one mature leaf per plant (ten per light

environment).

Results: Sun leaves had higher fenestrated area, perimeter, and stomatal density, suggesting structural adapta-

tions to high light. These traits may enhance thermal regulation by facilitating heat dissipation. Sun leaves had

lower SLA, indicating thicker, denser leaves better suited to high light and wind exposure. Lobulation ratios (leaf

dissection) were not different between sun and shade conditions. A principal component analysis explained

82.88% of the variation in the leaf traits, with 39 % of the variation attributed to fenestrated area, leaf perimeter,

and effective leaf area. Correlation analyses showed that fenestrated area, perimeter, and stomatal density were

positively associated (and negatively related to SLA), emphasizing the functional convergence of these traits,

adapting the leaf phenotype to light differences.

Conclusions: M. deliciosa modulates leaf morphology and structure to adapt to distinctive light conditions, with

fenestration, stomatal density, and SLA emerging as crucial traits. These findings underscore the significance of

environmental differences in driving leaf shape and structure.

Key words: functional traits; leaf dissection; phenotypic plasticity; plant morphology; stomatal density.

RESUMEN

Diferencias fenotípicas en hojas de sol y sombra de Monstera deliciosa (Araceae)

Introducción: Las hojas se encuentran entre los órganos más plásticos de las plantas, y su estructura, aunque

influenciada por la filogenia, puede mostrar una notable plasticidad fenotípica dentro de una misma especie en

https://doi.org/10.15517/rev.biol.trop..v73i1.56794

TERRESTRIAL ECOLOGY

2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

INTRODUCTION

Leaves are among the most plastic organs

in plants (Bradshaw, 2006; Kidner & Umbreen

2010; Nicotra et al., 2010; Reich et al., 1997;

Wright et al., 2004; Wright et al., 2017), with

their morphology, anatomy, and function

reflecting adaptations to environmental gra-

dients at the whole-plant level (Givnish, 1979;

Reich et al., 1997; Sultan, 1987; Wright et al.,

2004, Wright et al., 2017). While leaf structure

is shaped by phylogeny (Givnish, 1987; Hay,

2019; Klingenberg et al., 2012), plants also show

considerable leaf phenotypic plasticity within a

species in response to environmental gradients

(e.g., Martín-Sánchez et al., 2024). According

to the functional convergence hypothesis, selec-

tive pressures-such as light, nutrient availability,

and herbivory-converge on the leaf (Meinzer,

2003), making leaf structure a useful proxy for

assessing whole-plant resource allocation strat-

egies and adaptations to environmental changes

(Pierce et al., 2022). This justifies efforts to

identify integrative functional traits that con-

nect leaf structure to whole-plant performance,

from individual plants to ecosystems (de Bello

et al., 2010; Díaz et al., 2016; Funk et al., 2017;

Reich et al., 1997; Wright et al., 2004).

Key environmental factors such as nutri-

ent distribution, temperature, water avail-

ability, and light influence resource allocation

and plant function, impacting leaf structure

(Nicotra et al., 2010). Leaf structure further

determines energy absorption, affecting the leaf

energy balance (Michaletz et al., 2015; Nobel,

1999). Features like boundary layer thickness

and heat exchange can buffer leaves against

environmental fluctuations (Nobel, 1999). For

instance, small, narrow, and highly dissected

leaves have a thinner boundary layer and high-

er heat dissipation capacity through convec-

tion compared to larger, entire leaves (Givnish,

1979; Vogel, 2009). In dry ecosystems, sun-

exposed leaves are often smaller and more

dissected, with greater lobulation and higher

stomatal density than shade leaves, which expe-

rience more stable thermal conditions (Vogel,

2009). Increased lobulation supports heat dis-

sipation more effectively than angling leaves to

reduce light absorption (Vogel, 2009). Species

respuesta a gradientes ambientales. Monstera deliciosa, una trepadora tropical hemiepífita conocida por su alta

heteroblastia foliar, se adapta a diversas condiciones de luz. Esto convierte a la estructura foliar en un indicador

útil para evaluar las estrategias de asignación de recursos de toda la planta y sus adaptaciones a los cambios

ambientales.

Objetivo: Medir las diferencias morfológicas y estructurales entre hojas de sol y sombra utilizando nueve rasgos

foliares (longitud del pecíolo, ancho y largo de la hoja, área foliar efectiva, área fenestrada, perímetro de la hoja,

índice de lobulación, densidad estomática y área foliar específica -AFE-).

Métodos: Seleccionamos 20 plantas de M. deliciosa ampliamente separadas en el campus de la Universidad de

Costa Rica en 2022, ubicadas en condiciones contrastantes de sol y sombra, y medimos una hoja madura por

planta (diez en cada ambiente de luz).

Resultados: Las hojas de sol presentaron mayor área fenestrada, perímetro y densidad estomática, lo que sugiere

adaptaciones estructurales a la alta luminosidad. Estos rasgos podrían mejorar la regulación térmica al facilitar

la disipación de calor. Las hojas de sol presentaron menor AFE, lo que indica hojas más gruesas y densas, mejor

adaptadas a la exposición a la luz intensa y al viento. La proporción de lobulación (grado de disección de la hoja)

no mostró diferencias en hojas de sol y sombra. El análisis de componentes principales explicó el 82.88% de la

variación en los rasgos foliares, con el 39% de la variación atribuida al área fenestrada, perímetro de la hoja y área

foliar efectiva. Los análisis de correlación mostraron que el área fenestrada, el perímetro y la densidad estomática

estuvieron positivamente asociados (y negativamente relacionados con el AFE) como adaptación del fenotipo

foliar a las diferencias de luz.

Conclusiones: M. deliciosa ajusta la morfología y estructura foliar para adaptarse a condiciones lumínicas extre-

mas, con la fenestración, densidad estomática y SLA como caracteres clave. Estos hallazgos resaltan la importancia

de las diferencias ambientales en determinar la forma y estructura de las hojas.

Palabras clave: caracteres funcionales; densidad estomática; disección de hojas; morfología foliar; plasticidad

fenotípica.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

with pinnately compound leaves can dissi-

pate heat efficiently and lose individual leaflets

rather than entire blades (Balding & Cun-

ningham, 1976). The diversity in leaf size,

shape, spatial arrangement, phenology, and

heterophylly demonstrates the adaptive strate-

gies that align leaf structure with fluctuating

environmental conditions.

Plant functional traits serve as indica-

tors of ecological and life-history strategies

(Westoby et al., 2002), encompassing morpho-

logical, biochemical, physiological, structural,

and phenological traits that influence perfor-

mance and fitness (Cornelissen et al., 2003).

Specific leaf area (SLA), which represents the

fresh leaf area per unit dry mass, is a funda-

mental functional trait linking leaf quality to

structure and function (Reich et al., 1998; Reich

et al., 2003; Wright et al., 2004). SLA correlates

with photosynthetic rate, nitrogen content, leaf

lifespan, quantity and quality of defenses, and

growth rate, reflecting trade-offs between light

absorption and leaf construction costs, and

thus, it influences overall plant performance

and fitness (Reich et al., 1997). SLA is deter-

mined by internal leaf anatomy, tissue density,

and chemical properties (Poorter et al., 2014;

Villar et al., 2013), as well as by whole-plant

allocation strategies (Pierce et al., 2022). Since

SLA measures the cost of light interception at

the leaf level, it also affects leaf energy balance

and can serve as a proxy for acclimation to sun

and shade environments over a leaf’s lifetime

(Rozendaal et al., 2006).

The genus Monstera, known for high leaf

heteroblasty (Andrade et al., 2008; Madison,

1977), includes nomadic vines (Zotz, 2013) that

thrive on a range of substrates, such as trees

and rocks. Monstera deliciosa Liebm. adapts

to diverse light conditions, from sun-exposed

canopy sites to shaded understories. In the

shade, leaves tend to be smaller, with shorter

petioles, and reduced fenestration and lobula-

tion compared to those in well-lit environ-

ments (pers. obs). A mature M. deliciosa crown

may have both sun-exposed and shaded leaves,

with phenotypic adjustments likely following

light availability. Leaf fenestration, along with

dissection or lobulation, can be considered an

environmentally influenced trait (sensu Muir,

2013) as multiple environmental factors shape

its adaptive effects along light gradients.

This study examines the morphological

and structural differences between sun and

shade leaves of M. deliciosa, focusing on fen-

estration and lobulation. We predict (a) that

mature sun and shade leaves will differ in fenes-

trated area and lobulation ratio (leaf perimeter

relative to the square of effective area, exclud-

ing fenestrations). Highly fenestrated, dissected

leaves may dissipate heat effectively under sun

(Nicotra et al., 2008). We also anticipate (b) that

sun leaves will have higher stomatal density and

lower SLA than shade leaves, adapting to higher

radiation and wind exposure with increased

transpiration for cooling and a thicker, more

robust leaf structure. Overall, we expect sun

leaves to be smaller, more dissected and lobu-

lated, with higher stomatal density and lower

SLA compared to shade leaves.

Understanding the relationship between

leaf structure and light gradients addresses a

key question in plant physiology: adaptation

in structure and function to distinct environ-

ments. This exploratory study aims to inspire

future research on the role of fenestration and

lobulation in Monstera species with diverse leaf

morphologies.

MATERIALS AND METHODS

Site description: Data collection was con-

ducted in San Pedro de Montes de Oca, San

José, at the campus of the University of Costa

Rica (UCR, 9°56’09.1” N & 84°03’02.9” W,

1 200 m.a.s.l.). The site is in the Central Val-

ley, and the life zone classifies a tropical and

premontane rainforest (Holdridge & Grenke,

1971). The average annual rainfall is 1 700 mm,

and the average annual temperature is 22 °C

(Herrera & Gómez, 1993).

Study species: The genus Monstera has 35

species in Costa Rica (Cedeño-Fonseca et al.,

2022). The species M. deliciosa Liebm. (Ara-

ceae) is one of the most cultivated ornamental

4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

plants in the world (Cedeño-Fonseca et al.,

2022; Madison, 1977). It is distributed from

Mexico to Guatemala. It was introduced in

Costa Rica, where it can be found from 400-2

000 m.a.s.l. (Grayum, 2004). The growth habit

is hemiepiphytic or epiphytic scandent. Seed-

lings start on the ground and then colonize

a vertical substrate, displaying small, entire

leaves. The rhizomatous stem produces adven-

titious roots, enabling the plant to anchor itself

to various substrates, including rocks and trees.

The stem can lose contact with the ground but

sends feeder roots down. This pattern of habitat

colonization (starting life on the ground, then

colonizing the canopy while maintaining a root

connection on the ground) fits the definition

of a nomadic vine (Sperotto et al., 2020; Zotz,

2013). The leaves experience a wide range of

light gradients, from the understory to the

canopy, as the plant colonizes different light

environments, from highly shaded to highly

exposed sites. In M. deliciosa, leaf development

is highly plastic and seems associated with plant

age and light conditions. For instance, in repro-

ductive plants the leaves usually maintain a

regular phenotype in terms of size and number

of fenestrations, although in the highlands M.

deliciosa may develop smaller leaves (Cedeño-

Fonseca et al., 2020). The adult leaves of a

mature plant have very deep lobes (6 to 12 lobes

per leaf) and over 101 fenestrations, although

the number of fenestrations is usually very

regular (Cedeño-Fonseca et al., 2020).

Leaf selection according to distinct con-

ditions of sun and shade: We selected M. deli-

ciosa plants under distinctively different high

light and deep shade conditions during Sep-

tember, October, and November 2022. The light

environments of sun and shade were chosen to

maximize light differences (i.e., sun leaves were

clearly exposed to high light, and shade leaves

were chosen below several layers of sun leaves).

We chose only one mature, fully expanded leaf

per plant and per light environment, in widely

distributed M. deliciosa patches to make sure

that leaves belong to different individuals. In

total, we measured 20 leaves (one per patch), 10

for each light condition.

Quantification of leaf morphology and

structure: Each sampled leaf was photographed

in situ, with a large piece of white cloth placed

behind it to enhance contrast. To ensure accu-

rate measurements, the leaf surface was kept as

flat as possible, and a 50 cm ruler was included

in the frame for scale. Using ImageJ software

(Schneider et al., 2012), we measured the total

leaf area (including fenestrations), the fenes-

trated area, the effective leaf area (excluding

fenestrations), and the leaf perimeter based on

these photographs. Leaf length was measured

directly from the base of the leaf blade to the tip

using a measuring tape. Leaf width was deter-

mined by measuring from the tip of the sixth

lobe on the left side of the leaf blade (starting

from the base) to the tip of the sixth lobe on the

right side. The fenestration ratio was calculated

as the fenestrated area divided by the total leaf

area. The lobulation ratio, equivalent to the leaf

dissection index (Kincaid & Schneider, 1983),

was determined by dividing the leaf perimeter

by the square of the effective leaf area. We sepa-

rated lobes from fenestrations; but we recognize

that lobes begin as fenestrations by breaking

through the leaf margin and thus forming the

lobes (medium to small fenestrations remained

within the leaf margin). This was an arbitrary

distinction, but the purpose was to quantify

leaf lobulation separated from the fenestration

within the leaf margin. The length of the leaf

petiole was measured from the point of petiole

insertion on the stem to the beginning of the

leaf blade.

Specific leaf area (SLA): SLA (cm2/g) is

defined as the ratio of fresh leaf area to dry

weight (Poorter et al., 2009). A section of fresh

leaf area of 12.5 cm2 was obtained from the right

side of every leaf near the central vein. The dry

weight of this leaf section was measured after

placing it in an oven at 60 oC for 3 days or until

constant weight. Leaf mass was measured using

a PRACTUM224-1S analytical scale.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

Stomatal density: We took a 12.5 cm2 leaf

segment from the middle of the central vein

and at the end of the left lobe (abaxial surface)

and reported stomatal density (SD) as the

number of stomata (n stomata/mm2) within an

area of 3 mm2 at a magnification of 100x under

a light microscope using an imprint of a dried

layer of clear nail polish.

Statistical analysis

Correlation structure of leaf morpho-

logical traits: We examined the relationships

among nine traits describing leaf morphology

and degree of leaf lobulation (Table 1). First, we

calculated the Pearson correlation coefficients

for these traits (Fig. 1) and then used principal

component analysis (PCA) to summarize the

correlation structure. From the 11 variables

listed in Table 1, we selected nine: total leaf area

was excluded due to redundancy with effective

leaf area (correlation coefficient of 0.99), and

fenestration ratio was excluded as it showed a

high correlation (0.88) with fenestrated area,

leaving only the fenestrated area. The variables

entering the PCA were ln-transformed and

centered to remove artifacts caused by scale and

different units of measurement.

Fig. 1. Correlation matrix of nine ln-transformed morphological traits in 20 leaves of Monstera deliciosa. Values correspond

to the Pearson correlation coefficient for each variable combination. SD = stomatal density, SLA = specific leaf area.

6Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

Leaf shape and morphology were summa-

rized by the scores of the first three principal

components (eigenvalues > 1, 82.88 % of the

total variation), which were derived from the

nine selected traits. To assess differences in these

principal component scores between light con-

ditions (sun and shade), we performed one-way

MANOVA (Quinn & Keough, 2002). Following

a significant MANOVA result, we conducted

one-way ANOVAs on individual variables as

post hoc tests to detect specific differences

between sun and shade leaves. All analyses were

performed in R, using the PerformanceAnalyt-

ics, factoextra, and FactoMineR packages.

RESULTS

Differences between sun and shade leaves

were evident in the magnitude of effective leaf

area, fenestrated area (4.74 % of the effective

leaf area in sun leaves and 1.88 % in shade

leaves), fenestration ratio, leaf perimeter, and

stomatal density. All these variables had higher

magnitude in sun leaves, but SLA was higher

in shade leaves (Table 1). Positive correla-

tions were observed among fenestrated area,

fenestration ratio, leaf perimeter, and stomatal

density. The strongest positive correlation was

between petiole length and leaf width, followed

by the correlation between stomatal density and

fenestrated area. The strongest negative correla-

tion was found between lobulation ratio and

effective leaf area (Fig. 1).

Trait association and principal compo-

nent analysis: The principal component analy-

sis summarized the correlation structure of the

nine morphological traits into three compo-

nents, which explained 82.88 % of the variation

(Table 2). Fenestrated area, effective leaf area,

and leaf perimeter dominated the first compo-

nent (39.14 %); these are traits associated to leaf

size and shape. The second component (25.44

% of the variation) was dominated by lobula-

tion ratio, stomatal density, and SLA (SLA was

inversely related to the first two variables). The

third component (18.30 %) showed high load-

ings for leaf width and petiole length.

We ran a one-way MANOVA testing dif-

ferences between sun and shade leaves across

the scores of the first three principal compo-

nents. We found a strong effect of habitat differ-

ences in the scores of the principal components

(Hotelling-Lawley Trace3.16 = 4.74, p < 0.001),

with significant differences for the first (F1.18 =

8.04, p < 0.01) and second components (F1.18

= 17.15, p < 0.0001, Fig. 2, Fig. 3). Differences

among light environments were not significant

for the third component (F1.18 = 0.54, p = 0.47).

Tabl e 1

Leaf morphological traits measured in Monstera deliciosa on the campus of the University of Costa Rica, San Pedro, Costa

Rica, under sun and shade conditions.

Leaf trait Sun leaves Shade leaves

Petiole length (cm) 50.28 (4.43) 52.22 (3.51)

Leaf width (cm) 50.39 (5.11) 48.35 (3.14)

Leaf length (cm) 52.70 (4.58) 49.80 (3.27)

Total leaf area (cm2)1 598 (105.53) 1 500 (140.36)

Effective leaf area (cm2)1 522.18 (100.64) 1 471.85 (132.78)

Fenestrated area (cm2)75.81 (9.81) 28.14 (8.22)

Fenestration ratio 0.046 (0.005) 0.016 (0.003)

Leaf perimeter (cm) 809.84 (47.27) 659.28 (56.97)

Lobulation ratio (dissection index) 0.00037 (0.000035) 0.00033 (0.000034)

Stomatal density, stomata/cm2 17.53 (0-64) 10.83 (0.56)

SLA (cm2/g) 84.78 (2.14) 132.16 (4.36)

Values are means (± 1 S.E.) of 10 fully expanded, mature leaves per light environment.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

Tabl e 2

Principal component analysis summarizing the correlation structure of 9 leaf morphological characters in Monstera deliciosa.

In bold-face variables dominating a given component.

Principal component 1 Principal component 2 Principal component 3

Eigenvalue 3.523097 2.28 1.64

Percentage of variation 39.14 25.44 18.30

Cumulative percentage of variation 39.14 64.58 82.88

lnSD 0.29 -0.46 -0.15

Lnpetiole-lenght 0.26 0.30 0.54

Lnleaf-width 0.31 0.20 0.54

Lnleaf-lenght 0.21 0.28 -0.36

Lnfenestrated-area 0.48 -0.18 0.0029

Lneffective-leaf-area 0.40 0.30 -0.288

Lnleaf-perimeter 0.44 -0.13 0.058

Ln-SLA -0.30 0.44 0.092

lnlobulation-ratio -0.18 -0.48 0.40

The PCA used the ln-transformed values of the variables. SD = stomatal density, SLA = specific leaf area.

Fig. 2. Principal component analysis applied to nine ln-transformed morphological traits in Monstera deliciosa according

to light environment. Ellipses show 95 % confidence intervals. (A) The first component was dominated by fenestrated area,

effective leaf area and leaf perimeter, whereas the second component was dominated by stomatal density and lobulation ratio

which maintained a negative correlation with SLA. (B) The third component was dominated by petiole length and leaf width.

The first and second component separated sun and shade leaves. SD = stomatal density, SLA = specific leaf area.

8Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

Test of prediction a: mature sun and shade

leaves will vary in fenestrated area and lobula-

tion ratio, which will be higher in sun leaves.

Post hoc one-way ANOVAs were conduct-

ed for fenestrated area and lobulation ratio,

using ln-transformed values to meet normal-

ity and homogeneity of variance assumptions.

Fenestrated area showed higher values in sun

leaves (F1.18 = 12.74, p < 0.001), whereas dif-

ferences were not significant for the lobulation

ratio (F1.18 = 0.7, p > 0.05).

Test of prediction b: sun leaves will have

higher stomatal density and lower SLA than

shade leaves.

Similarly, post hoc one-way ANOVAs were

conducted for stomatal density and SLA, using

ln-transformed values to meet assumptions of

normality and homogeneity of variance. We

found higher stomatal density in sun leaves

(F1.18 = 60.86, p < 0.0001), and higher SLA val-

ues in shade leaves (F1.18 = 109.4, p < 0.0001).

DISCUSSION

Monstera deliciosa exhibits distinct leaf

phenotypes under sun and shade conditions.

Sun leaves had a larger effective leaf area, more

fenestrated area, a higher fenestration ratio,

greater leaf perimeter, higher stomatal density,

and lower SLA compared to shade leaves. The

first principal component was primarily domi-

nated by effective leaf area, leaf perimeter, and

fenestrated area, which correlated with stomatal

density and SLA. When examined separately,

these traits (except SLA) were all higher in

sun leaves, supporting our initial prediction

of increased fenestration and stomatal density

in sun leaves (and lower SLA in sun leaves).

However, the fenestrated area comprised only a

small proportion of the effective leaf area.

No significant differences in lobulation

ratio were observed between sun and shade

leaves, indicating a similar degree of dissec-

tion. Sun and shade leaves also had a similar

total area and effective leaf area. This suggests

that differences between sun and shade leaves

extend beyond size and shape and are mostly

determined by structural and functional traits,

such as higher stomatal density and fenestrated

area in sun leaves and higher SLA in shade

leaves.

As leaf size increases, so does the area of

fenestrations and the leaf perimeter, so that

larger leaves have more fenestrations, and pro-

portionally larger perimeter due to correlated

Fig. 3. Scores of three principal components based on the combined variation of nine Ln-transformed morphological traits

in Monstera deliciosa across sun and shade light environments. Paired comparisons reflect the scores for sun and shade leaves

within each component, which together explained 82.88% of the variation. Different letters indicate significant differences,

while the same letter denotes a lack of significant differences.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

growth. Also, it might seem contradictory that

the fenestrated area and the leaf perimeter

were decoupled from the lobulation ratio. We

attribute this discrepancy to the fact that the

lobulation ratio is correlated primarily with the

amount of leaf area, whereas the fenestrated

area and the leaf perimeter are also indicative

of leaf shape. Therefore, while leaf size is an

important morphological trait, it may not fully

capture the subtle variation associated with the

adjustment to light gradients mediated through

changes in leaf shape (see Li et al., 2020) and

structure (i.e., SLA, Kidner & Umbreen 2010).

Our study analyzed only one leaf per plant,

which limited our ability to assess whether the

light intensity affecting that leaf influenced its

morphology, structure, and size independently

of the light conditions experienced by the rest

of the crown, as affected by the plant’s resource

allocation strategy (Francis & Gilman, 2019).

The fenestrated area, despite its small mag-

nitude relative to total leaf area, increased in

sun leaves, along with stomatal density. It is

plausible that sun leaves are likely subject to

higher hydraulic demands (López-Portillo et

al., 2000; Muir, 2013). More dissected leaves

(i.e., compound leaves) are more common in

hot and dry environments at the top of the can-

opy (Givnish, 1979; Muir, 2013; Nicotra et al.,

2010). As more fenestrations were associated

to higher stomatal density, leaf thermal regu-

lation is likely achieved through an increased

fenestrated area as well as through stomatal

regulation. Stomatic conductance data is neces-

sary to test this idea as well as a more detailed

analysis of the structure and size of stomata and

its association with leaf thickness and vascular

architecture (Kidner & Umbreen, 2010; Pérez-

Bueno et al., 2022).

The fenestrated area made a low percent-

age of the effective leaf area, which indicates

that changes in leaf shape are subtle under

contrasting light environments, even though

the fenestrated area for sun leaves was twice

that of shade leaves. Thus, it is likely that M.

deliciosa modulates its adaptation to differ-

ent light regimes as the leaf develops through

small changes in leaf shape. Since lobulation

ratio is the proportion of leaf perimeter over

the square of effective leaf area it is possible

that the lobulation ratio did not capture small

changes in leaf dissection, which were pos-

sibly more related to the fenestrated area and

to the leaf perimeter. Longitudinal data are

required to better control for environmental

variation during leaf development. Although

M. deliciosa can produce new leaves in the

shade, it is also possible that the leaves currently

in the shade would have initially developed

under sun conditions. This scenario may indi-

cate a significant capacity for post-expansion

acclimatization to low light, which has been

rarely documented in canopy plants (Avalos &

Mulkey, 1999; Avalos & Mulkey, 2014). Post-

expansion acclimation occurs more readily in

sun leaves, driven primarily by changes in pho-

tochemistry rather than structural adjustments

(Brooks et al., 1996). The significant differences

in SLA between sun and shade leaves suggest

long-term adaptation to their respective light

environments, supporting the idea that each

leaf type developed specifically within its native

conditions. However, validating this hypothesis

would require a long-term monitoring study to

track leaf crown development, measuring how

leaves acclimate as they progress through a

range of light conditions during growth.

The morphological and structural differ-

ences of sun and shade leaves in M. deliciosa

(i.e., increased fenestrated area and stomatal

density in sun leaves and higher SLA in shade

leaves) underscore the plant’s capacity to modify

its leaf phenotype to contrasting light environ-

ments. These findings highlight the importance

of subtle leaf shape modifications and indicate a

potential for post-expansion acclimation, espe-

cially in sun leaves, to optimize performance

under varying light conditions.

We hope that the methods described here

will serve as a basis to expand the analysis of

the function of fenestrations and the influence

of leaf shape and size on leaf function in Ara-

ceae vines, including other Monstera species

with different degrees of fenestration. Further

research along these lines will help to finally

answer some of the most recurring questions

10 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73: e56794, enero-diciembre 2025 (Publicado Jun. 30, 2025)

on the functional role of leaf heteroblasty (Kid-

ner & Umbreen 2010), such as the impact of

fenestration on the internal crown light envi-

ronment of M. deliciosa, as well as how changes

in leaf structure and function, expressed over

time, facilitate habitat colonization.

Ethical statement: The authors declare

that they all agree with this publication and

made significant contributions; that there is no

conflict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are fully

and clearly stated in the acknowledgments sec-

tion. A signed document has been filed in the

journal archives.

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