[XtraChartsLocalizableCategory(XtraChartsCategory.Appearance)]
public MarkerKind MeanMarkerKind { get; set; }

<XtraChartsLocalizableCategory(XtraChartsCategory.Appearance)>
Public Property MeanMarkerKind As MarkerKind

using DevExpress.XtraCharts;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;

namespace BoxPlotChart {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e) {
            Series series = new Series("Box Plot", ViewType.BoxPlot);
            series.DataSource = DataPoint.GetDataPoints();
            series.SetBoxPlotDataMembersWithOutliers("Argument", "Min", "Quartile1", "Median", "Quartile3", "Max", "Mean", "Outliers");
            chartControl1.Series.Add(series);

            BoxPlotSeriesView view = series.View as BoxPlotSeriesView;
            view.EqualBoxWidth = true;
            view.Color = Color.CadetBlue;
            view.CapWidthPercentage = 50;
            view.MeanAndMedianColor = Color.Black;
            view.MeanMarkerKind = MarkerKind.ThinCross;
            view.MeanMarkerSize = 10;
            view.Border.Color = Color.Black;
            view.Border.Thickness = 1;
            view.Border.Visibility = DevExpress.Utils.DefaultBoolean.True;

            XYDiagram diagram = chartControl1.Diagram as XYDiagram;
            diagram.AxisX.Tickmarks.MinorVisible = false;
        }
    }
    public class DataPoint {
        public string Argument { get; set; }
        public double Min { get; set; } 
        public double Max { get; set; }
        public double Quartile1 { get; set; }
        public double Quartile3 { get; set; }
        public double Median { get; set; }
        public double Mean { get; set; }
        public double[] Outliers { get; set; }
        public DataPoint(string argument, double min, double max, double q1, double q3, double median, double mean, double[] outliers) {
            this.Argument = argument;
            this.Min = min;
            this.Max = max;
            this.Quartile1 = q1;
            this.Quartile3 = q3;
            this.Median = median;
            this.Mean = mean;
            this.Outliers = outliers;
        }
        public static List<DataPoint> GetDataPoints() {
            List<DataPoint> data = new List<DataPoint> {
                new DataPoint("June", 46, 94, 64, 76, 70, 73, new double[]{ 30, 96.3, 99.56 }),
                new DataPoint("July", 33, 121, 66, 88, 77, 75, new double[]{ 20, 22, 132.7 }),
                new DataPoint("August", 10, 90, 40, 60, 50, 55, new double[]{ 4, 5, 95.4, 99.3, 109 })
            };
            return data;
        }
    }
}

Imports DevExpress.XtraCharts
Imports System
Imports System.Collections.Generic
Imports System.Drawing
Imports System.Windows.Forms

Namespace BoxPlotChart
    Public Partial Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
            Dim series As Series = New Series("Box Plot", ViewType.BoxPlot)
            series.DataSource = DataPoint.GetDataPoints()
            series.SetBoxPlotDataMembersWithOutliers("Argument", "Min", "Quartile1", "Median", "Quartile3", "Max", "Mean", "Outliers")
            chartControl1.Series.Add(series)
            Dim view As BoxPlotSeriesView = TryCast(series.View, BoxPlotSeriesView)
            view.EqualBoxWidth = True
            view.Color = Color.CadetBlue
            view.CapWidthPercentage = 50
            view.MeanAndMedianColor = Color.Black
            view.MeanMarkerKind = MarkerKind.ThinCross
            view.MeanMarkerSize = 10
            view.Border.Color = Color.Black
            view.Border.Thickness = 1
            view.Border.Visibility = DevExpress.Utils.DefaultBoolean.[True]
            Dim diagram As XYDiagram = TryCast(chartControl1.Diagram, XYDiagram)
            diagram.AxisX.Tickmarks.MinorVisible = False
        End Sub
    End Class

    Public Class DataPoint
        Public Property Argument As String
        Public Property Min As Double
        Public Property Max As Double
        Public Property Quartile1 As Double
        Public Property Quartile3 As Double
        Public Property Median As Double
        Public Property Mean As Double
        Public Property Outliers As Double()

        Public Sub New(ByVal argument As String, ByVal min As Double, ByVal max As Double, ByVal q1 As Double, ByVal q3 As Double, ByVal median As Double, ByVal mean As Double, ByVal outliers As Double())
            Me.Argument = argument
            Me.Min = min
            Me.Max = max
            Me.Quartile1 = q1
            Me.Quartile3 = q3
            Me.Median = median
            Me.Mean = mean
            Me.Outliers = outliers
        End Sub

        Public Shared Function GetDataPoints() As List(Of DataPoint)
            Dim data As List(Of DataPoint) = New List(Of DataPoint) From {
                New DataPoint("June", 46, 94, 64, 76, 70, 73, New Double() {30, 96.3, 99.56}),
                New DataPoint("July", 33, 121, 66, 88, 77, 75, New Double() {20, 22, 132.7}),
                New DataPoint("August", 10, 90, 40, 60, 50, 55, New Double() {4, 5, 95.4, 99.3, 109})
            }
            Return data
        End Function
    End Class
End Namespace