Leaf shape in plants plays important roles in water use, canopy structure, and physiological tolerances to abiotic stresses; all important traits for the future development and sustainability of grapevine cultivation. Historically, researchers have used ampelography, the study of leaf shape in grapevines, to differentiate <i>Vitis</i> species and cultivars based on finite leaf attributes. However, ampelographic measurements have limitations and new methods for quantifying shape are now available. We paired an analysis of finite trait attributes with a 17-point landmark survey and generalized Procrustes analysis (GPA) to reconstruct grapevine leaves digitally from five interspecific hybrid mapping families. Using the reconstructed leaves, we performed three types of quantitative trait loci (QTL) analyses to determine the genetic architecture that defines leaf shape. In the first analysis, we compared several important ampelographic measurements as finite trait QTL. In the second and third analyses, we identified significant shape variation <i>via</i> principal components analysis (PCA) and using a multivariate least squares interval mapping (MLSIM) approach. In total, we identified 271 significant QTL across the three measures of leaf shape and identified specific QTL hotspots in the grape genome which appear to drive major aspects of grapevine leaf shape. Historically, researchers have used ampelography, the study of leaf shape in grapevines, to differentiate Vitis species and cultivars based on finite leaf attributes. However, ampelographic measurements have limitations and new methods for quantifying shape are now available. We paired an analysis of finite trait attributes with a 17-point landmark survey and generalized Procrustes analysis (GPA) to reconstruct grapevine leaves digitally from five interspecific hybrid mapping families. Using the reconstructed leaves, we performed three types of quantitative trait loci (QTL) analyses to determine the genetic architecture that defines leaf shape. Leaf shape and form have been thought to contribute to plant speciation and survival through conferring adaptive advantages. As reviewed by different authors ( Givnish, 1979 ; Givnish, 1987 ; Nicotra et al., 2011 ), plant leaf shape could affect temperature regulation, photosynthetic capacity, water use, and numerous other traits. A common theme regarding the ecophysiological importance of leaf shape is that leaf shape varies by climate. Evidence from fossilized leaves suggest that colder temperature climates select for leaves with larger and more abundant serrations as well as higher leaf dissection ( Royer et al., 2005 ; Peppe et al., 2011 ). Contrary to the trends of higher serration with cooler climates, leaf size and shape may also have large impacts on leaf temperature due to the rate of heat transfer across the boundary layer thickness on leaf surfaces. Heat dissipation from small leaves is faster than that from large leaves due to a reduced boundary layer and lobed leaves are predicted to also have faster heat transfer due to disruption of this layer. Lobed leaves may also have higher hydraulic efficiency due to their relative reduction in minor veins, which greatly increase the hydraulic resistance of the transpiration column ( Sack and Holbrook, 2006 ; Nicotra et al., 2011 ). For leaf morphology, 18 different finite traits ( Galet, 1979 ; OIV, 2018 ) were mapped to 12 of 19 chromosomes. Substantial overlap of different trait QTL were observed on chromosome 1 and the inference was that these traits were related to sinus formation ( Welter et al., 2007 ), or more generally, “lobiness”. The objective of this study was to examine the genetic architecture of grapevine leaf shape through examining the shape of leaves from five different grapevine mapping families. We leveraged whole genome, genotyping-by-sequencing single nucleotide polymorphism (SNP) marker based genetic maps and three methods of evaluating leaf shape in order to investigate what regions of the genome contribute to leaf shape differences. Results demonstrate major and minor clusters of QTL in the grape genome that seem to partition based on prominent shape attributes, such as lobiness, as well as by species or genotype. Materials and Methods Plant Materials The five mapping families for this study were derived from the interspecific hybridization of diploid (2n = 38) Vitis species ( Table 1 ; Figure 1 ). For example, V. rupestris B38 has a reniform leaf shape, whereas “Chardonnay” has an orbicular leaf shape. Differences in lobing patterns and the petiolar sinus can also be observed across the parents. Box plots depict the phenotypic distribution of each finite trait attribute within each of the five mapping families in Supplementary Figure 1 , and comparisons of finite trait measurements for each family are presented in Supplementary Table 1 . In general, V. cinerea has the longest leaves, V. rupestris has the shortest. “Cabernet Sauvignon” has the most lobed shape of all the parents while Illinois 547-1 and V. cinerea are the least lobed. V. The first is a Vitis ortholog of the JAGGED gene (Vitvi01g01939; VIT_01s0011g03600), a gene that has been shown to encode a zinc finger protein promoting leaf tissue development, specifically affecting leaf serrations in Arabidopsis ( Dinneny et Future mapping efforts in populations with even greater leaf morphology differences may elucidate the key genes in the lobiness loci that could be targets for gene editing in existing grape cultivars. Our study helps lay the foundation needed for future marker assisted based breeding efforts for controlling aspects of leaf canopies in grapevines and other crop species. Selecting for designer leaves might be an important aspect in the development of new cultivars with idealized canopy structure. Data Availability Statement The datasets generated for this study can be found in the NCBI SRA http://www.ncbi.nlm.nih.gov/bioproject/281110 .