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  <xsd:element id="istr_BankingRegulationCommonEquityTierOneRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationCommonEquityTierOneRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTierOneLeverageCapitalCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTierOneLeverageCapitalCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTierOneLeverageCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTierOneLeverageCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTierOneRiskbasedCapitalCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTierOneRiskbasedCapitalCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTierOneRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTierOneRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTotalRiskbasedCapitalCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTotalRiskbasedCapitalCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_BankingRegulationTotalRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" name="BankingRegulationTotalRiskbasedCapitalRatioCapitalAdequacyMinimumIncludingConservationBuffer" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_CheahaFinancialGroupMember" name="CheahaFinancialGroupMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_CheahaStatutoryTrustIMember" name="CheahaStatutoryTrustIMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_CommercialRealEstateLoanMember" name="CommercialRealEstateLoanMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_CommitmentToFundInvestmentInSBICQualifiedFunds" name="CommitmentToFundInvestmentInSBICQualifiedFunds" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_CorporateStockAndMutualFundsMember" name="CorporateStockAndMutualFundsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_CustomersMember" name="CustomersMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DebtSecuritiesAvailableforsaleUnrealizedLossPositionPercentOfAmortizedCostOfInvestmentSecuritiesPortfolio" name="DebtSecuritiesAvailableforsaleUnrealizedLossPositionPercentOfAmortizedCostOfInvestmentSecuritiesPortfolio" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesAvailableforsaleUnrealizedLossPositionPercentOfSecuritiesCostBasis" name="DebtSecuritiesAvailableforsaleUnrealizedLossPositionPercentOfSecuritiesCostBasis" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss1" name="DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerFairValue1" name="DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPosition12MonthsOrLongerFairValue1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss1" name="DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsFairValue1" name="DebtSecuritiesHeldtomaturityContinuousUnrealizedLossPositionLessThan12MonthsFairValue1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityFairValueDisclosure" name="DebtSecuritiesHeldtomaturityFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityUnrealizedLossPositionAccumulatedLoss1" name="DebtSecuritiesHeldtomaturityUnrealizedLossPositionAccumulatedLoss1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityUnrealizedLossPositionFairValue1" name="DebtSecuritiesHeldtomaturityUnrealizedLossPositionFairValue1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DebtSecuritiesHeldtomaturityUnrealizedLossPositionFairValueTableTextBlock" name="DebtSecuritiesHeldtomaturityUnrealizedLossPositionFairValueTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DeferredCompensationArrangementWithIndividualMonthlyDistribution" name="DeferredCompensationArrangementWithIndividualMonthlyDistribution" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DeferredCompensationArrangementWithIndividualReducedPaymentsMaximumAgeUponTermination" name="DeferredCompensationArrangementWithIndividualReducedPaymentsMaximumAgeUponTermination" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DeferredCompensationArrangementWithIndividualRequisiteAgeOfEmployees" name="DeferredCompensationArrangementWithIndividualRequisiteAgeOfEmployees" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DeferredTaxAssetsBasisDifferenceInAcquiredAssetsAndLiabilities" name="DeferredTaxAssetsBasisDifferenceInAcquiredAssetsAndLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DeferredTaxAssetsOperatingLeaseLiability" name="DeferredTaxAssetsOperatingLeaseLiability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DeferredTaxAssetsUnearnedLoanFees" name="DeferredTaxAssetsUnearnedLoanFees" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DeferredTaxLiabilitiesBasisDifferenceInAcquiredAssetsAndLiabilities" name="DeferredTaxLiabilitiesBasisDifferenceInAcquiredAssetsAndLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DeferredTaxLiabilitiesFederalHomeLoanBankStockDividend" name="DeferredTaxLiabilitiesFederalHomeLoanBankStockDividend" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DefinedBenefitPlanEligibilityForParticipationRequisiteAgeOfEmployees" name="DefinedBenefitPlanEligibilityForParticipationRequisiteAgeOfEmployees" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DefinedContributionPlanAwardRequisiteServicePeriod" name="DefinedContributionPlanAwardRequisiteServicePeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DefinedContributionPlanEmployerDiscretionaryContributionAmountAwardVestingPeriod" name="DefinedContributionPlanEmployerDiscretionaryContributionAmountAwardVestingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DefinedContributionPlanEmployerDiscretionaryContributionAmountTotalAwardVestingPeriod" name="DefinedContributionPlanEmployerDiscretionaryContributionAmountTotalAwardVestingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DefinedContributionPlanEmployersDiscretionaryContributionAnnualVestingPercentage" name="DefinedContributionPlanEmployersDiscretionaryContributionAnnualVestingPercentage" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:percentItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_DepositsPublicFundsAmount" name="DepositsPublicFundsAmount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_DepreciationAndAmortizationMember" name="DepreciationAndAmortizationMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DerivativeCollateralPost" name="DerivativeCollateralPost" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_DistributionsFromInvestments" name="DistributionsFromInvestments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="istr_DividendIncomeFromSubsidiary" name="DividendIncomeFromSubsidiary" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_DocumentAndEntityInformation" name="DocumentAndEntityInformation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_DueFromBankSubsidiary" name="DueFromBankSubsidiary" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_EmployeesAndDirectorsMember" name="EmployeesAndDirectorsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_EmployeesMember" name="EmployeesMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_EquitySecuritiesHeldInCorrespondentBanksMember" name="EquitySecuritiesHeldInCorrespondentBanksMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_FarmlandMember" name="FarmlandMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_FederalHomeLoanBankLongTermBorrowingsFairValueDisclosure" name="FederalHomeLoanBankLongTermBorrowingsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_FederalHomeLoanBankStockDividends" name="FederalHomeLoanBankStockDividends" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="istr_FinancingReceivableImpairedDuringPeriodAllowanceForCreditLossesIndividuallyEvaluatedForImpairment" name="FinancingReceivableImpairedDuringPeriodAllowanceForCreditLossesIndividuallyEvaluatedForImpairment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="istr_FinancingReceivableImpairedDuringPeriodGross" name="FinancingReceivableImpairedDuringPeriodGross" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="istr_FinancingReceivableNonaccrualWithAllowance" name="FinancingReceivableNonaccrualWithAllowance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_FirstCommunityLouisianaStatutoryTrustIMember" name="FirstCommunityLouisianaStatutoryTrustIMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_ForwardStartingInterestRateSwapMember" name="ForwardStartingInterestRateSwapMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_GainLossOnSalesOfForeclosedAssets" name="GainLossOnSalesOfForeclosedAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_GreaterThanNinetyDaysAndAccruingMember" name="GreaterThanNinetyDaysAndAccruingMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_ImpairedFinancingReceivableMeasurementInput" name="ImpairedFinancingReceivableMeasurementInput" nillable="true" substitutionGroup="xbrli:item" type="xbrli:decimalItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_IncomeLossBeforeEquityInUndistributedIncomeLossOfSubsidiaryIncomeTaxes" name="IncomeLossBeforeEquityInUndistributedIncomeLossOfSubsidiaryIncomeTaxes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="istr_IncreaseDecreaseInDueFromBankSubsidiary" name="IncreaseDecreaseInDueFromBankSubsidiary" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="istr_IncreaseDecreaseInShorttermFhlbAdvances" name="IncreaseDecreaseInShorttermFhlbAdvances" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element id="istr_InterestBearingDepositLiabilitiesFairValueDisclosure" name="InterestBearingDepositLiabilitiesFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_InterestbearingDomesticDepositBrokeredDemandDeposits" name="InterestbearingDomesticDepositBrokeredDemandDeposits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_InterestbearingDomesticDepositBrokeredTimeDeposits" name="InterestbearingDomesticDepositBrokeredTimeDeposits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_InvestmentInTrust" name="InvestmentInTrust" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_KeyPersonnelMember" name="KeyPersonnelMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_LoanParticipationsAndWholeLoansSoldToAndServicedForOthersNotOnBalanceSheet" name="LoanParticipationsAndWholeLoansSoldToAndServicedForOthersNotOnBalanceSheet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_LoanParticipationsAndWholeLoansSoldToAndServicedForOthersUnpaidPrincipalBalance" name="LoanParticipationsAndWholeLoansSoldToAndServicedForOthersUnpaidPrincipalBalance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_LoanPortfolioMember" name="LoanPortfolioMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_LondonInterbankOfferRateMember" name="LondonInterbankOfferRateMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_ManagementServiceFeesToSubsidiaryBank" name="ManagementServiceFeesToSubsidiaryBank" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_MarketableSecuritiesAndMutualFundsMember" name="MarketableSecuritiesAndMutualFundsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_MeasurementInputCollateralDiscountsAndDiscountRatesMember" name="MeasurementInputCollateralDiscountsAndDiscountRatesMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_MeasurementInputCollateralDiscountsAndEstimatedCostsToSellMember" name="MeasurementInputCollateralDiscountsAndEstimatedCostsToSellMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_MinimumServicePeriodForParticipationInDefinedBenefitPlan" name="MinimumServicePeriodForParticipationInDefinedBenefitPlan" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_MultifamilyLoansMember" name="MultifamilyLoansMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_NatureOfOperationsPolicyPolicyTextBlock" name="NatureOfOperationsPolicyPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_NetIncomeLossAllocatedToCommonStockholdersBasic" name="NetIncomeLossAllocatedToCommonStockholdersBasic" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_NonemployeeDirectorsAndCertainOfficersMember" name="NonemployeeDirectorsAndCertainOfficersMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_NoninterestBearingDepositLiabilitiesFairValueDisclosure" name="NoninterestBearingDepositLiabilitiesFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element abstract="true" id="istr_NoteToFinancialStatementDetailsTextual" name="NoteToFinancialStatementDetailsTextual" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_NotesToFinancialStatements" name="NotesToFinancialStatements" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_NotesToFinancialStatementsAbstract" name="NotesToFinancialStatementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_NumberOfBankBranchesClosed" name="NumberOfBankBranchesClosed" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_OffbalancesheetAllowanceForCreditLossTableTextBlock" name="OffbalancesheetAllowanceForCreditLossTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_OffsettingAssetsAndLiabilitiesTableTextBlock" name="OffsettingAssetsAndLiabilitiesTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_OffsettingInterestRateSwapMember" name="OffsettingInterestRateSwapMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_OneFourFamilyMember" name="OneFourFamilyMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_OneToFourFamilyResidentialPropertyMember" name="OneToFourFamilyResidentialPropertyMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_OtherFinancialInstitutionsMember" name="OtherFinancialInstitutionsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_OtherRealEstateOwnedFairValueDisclosure" name="OtherRealEstateOwnedFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant"/>
  <xsd:element id="istr_OtherRealEstateOwnedTransfersFromBankPremisesAndEquipment" name="OtherRealEstateOwnedTransfersFromBankPremisesAndEquipment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="istr_OtherRealEstateOwnedWriteDowns" name="OtherRealEstateOwnedWriteDowns" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_PolicyTable" name="PolicyTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_PreferredStockConvertibleForcedConversionTriggerPrice" name="PreferredStockConvertibleForcedConversionTriggerPrice" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType" xbrli:periodType="instant"/>
  <xsd:element id="istr_PreferredStockConvertibleThresholdConsecutiveTradingDays" name="PreferredStockConvertibleThresholdConsecutiveTradingDays" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_PreferredStockConvertibleThresholdTradingDays" name="PreferredStockConvertibleThresholdTradingDays" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_ProceedsFromIssuanceOfPrivatePlacementNet" name="ProceedsFromIssuanceOfPrivatePlacementNet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element id="istr_ProvisionForOtherRealEstateOwned" name="ProvisionForOtherRealEstateOwned" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_RestrictedStockAndRestrictedStockUnitsMember" name="RestrictedStockAndRestrictedStockUnitsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_SalariesAndEmployeeBenefitsMember" name="SalariesAndEmployeeBenefitsMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_ScheduledMaturitiesOfTimeDepositsTableTableTextBlock" name="ScheduledMaturitiesOfTimeDepositsTableTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_StatementOfOtherComprehensiveIncomeAbstractDomain" name="StatementOfOtherComprehensiveIncomeAbstractDomain" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
  <xsd:element id="istr_TimeDeposits250000AndAbove" name="TimeDeposits250000AndAbove" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant"/>
  <xsd:element id="istr_TransferFromBankPremisesAndEquipmentToOtherAssets" name="TransferFromBankPremisesAndEquipmentToOtherAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_WFBMember" name="WFBMember" nillable="true" substitutionGroup="xbrli:item" type="dtr-types:domainItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-13-stockholders-equity-accumulated-other-comprehensive-income-loss-details" name="statement-statement-note-13-stockholders-equity-accumulated-other-comprehensive-income-loss-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-14-stockbased-compensation-schedule-of-stock-option-activity-details" name="statement-statement-note-14-stockbased-compensation-schedule-of-stock-option-activity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-14-stockbased-compensation-schedule-of-stock-option-valuation-assumptions-details" name="statement-statement-note-14-stockbased-compensation-schedule-of-stock-option-valuation-assumptions-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-16-income-taxes-summary-of-provision-for-federal-income-taxes-details" name="statement-statement-note-16-income-taxes-summary-of-provision-for-federal-income-taxes-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-17-fair-values-of-financial-instruments-assets-and-liabilities-measured-at-fair-value-on-recurring-basis-details" name="statement-statement-note-17-fair-values-of-financial-instruments-assets-and-liabilities-measured-at-fair-value-on-recurring-basis-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-17-fair-values-of-financial-instruments-quantitative-information-about-significant-unobservable-inputs-used-in-fair-value-measurement-details" name="statement-statement-note-17-fair-values-of-financial-instruments-quantitative-information-about-significant-unobservable-inputs-used-in-fair-value-measurement-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-17-fair-values-of-financial-instruments-reconciliation-for-assets-measured-at-fair-value-on-recurring-basis-using-significant-unobservable-inputs-details" name="statement-statement-note-17-fair-values-of-financial-instruments-reconciliation-for-assets-measured-at-fair-value-on-recurring-basis-using-significant-unobservable-inputs-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-19-commitments-and-contingencies-commitments-to-extend-credit-details" name="statement-statement-note-19-commitments-and-contingencies-commitments-to-extend-credit-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-19-commitments-and-contingencies-summary-of-acl-on-unfunded-loan-commitments-details" name="statement-statement-note-19-commitments-and-contingencies-summary-of-acl-on-unfunded-loan-commitments-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-amortized-cost-and-fair-value-of-investment-securities-classified-as-afs-details" name="statement-statement-note-2-investment-securities-amortized-cost-and-fair-value-of-investment-securities-classified-as-afs-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-contractual-maturity-details" name="statement-statement-note-2-investment-securities-contractual-maturity-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-sales-of-investments-classified-as-afs-details" name="statement-statement-note-2-investment-securities-sales-of-investments-classified-as-afs-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-summary-of-continuous-unrealized-loss-position-for-securities-classified-as-afs-details" name="statement-statement-note-2-investment-securities-summary-of-continuous-unrealized-loss-position-for-securities-classified-as-afs-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-summary-of-continuous-unrealized-loss-position-for-securities-classified-as-htm-details" name="statement-statement-note-2-investment-securities-summary-of-continuous-unrealized-loss-position-for-securities-classified-as-htm-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-2-investment-securities-tables" name="statement-statement-note-2-investment-securities-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-21-parent-company-only-financial-statements-balance-sheets-details" name="statement-statement-note-21-parent-company-only-financial-statements-balance-sheets-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-21-parent-company-only-financial-statements-statements-of-cash-flows-details" name="statement-statement-note-21-parent-company-only-financial-statements-statements-of-cash-flows-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-21-parent-company-only-financial-statements-statements-of-operations-details" name="statement-statement-note-21-parent-company-only-financial-statements-statements-of-operations-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-21-parent-company-only-financial-statements-tables" name="statement-statement-note-21-parent-company-only-financial-statements-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-22-earnings-per-common-share-antidilutive-securities-details" name="statement-statement-note-22-earnings-per-common-share-antidilutive-securities-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-22-earnings-per-common-share-earnings-per-share-details" name="statement-statement-note-22-earnings-per-common-share-earnings-per-share-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-3-loans-and-allowance-for-credit-losses-loan-portfolio-by-category-and-credit-quality-indicator-details" name="statement-statement-note-3-loans-and-allowance-for-credit-losses-loan-portfolio-by-category-and-credit-quality-indicator-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-3-loans-and-allowance-for-credit-losses-loans-to-related-parties-details" name="statement-statement-note-3-loans-and-allowance-for-credit-losses-loans-to-related-parties-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-3-loans-and-allowance-for-credit-losses-schedule-of-nonaccrual-loans-details" name="statement-statement-note-3-loans-and-allowance-for-credit-losses-schedule-of-nonaccrual-loans-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-3-loans-and-allowance-for-credit-losses-summary-of-loans-by-categories-details" name="statement-statement-note-3-loans-and-allowance-for-credit-losses-summary-of-loans-by-categories-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-6-leases-quantitative-information-regarding-operating-leases-details" name="statement-statement-note-6-leases-quantitative-information-regarding-operating-leases-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-6-leases-tables" name="statement-statement-note-6-leases-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-7-goodwill-and-other-intangible-assets-tables" name="statement-statement-note-7-goodwill-and-other-intangible-assets-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
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  <xsd:element abstract="true" id="istr_statement-statement-note-8-deposits-scheduled-maturates-of-time-deposits-details" name="statement-statement-note-8-deposits-scheduled-maturates-of-time-deposits-details" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-note-8-deposits-tables" name="statement-statement-note-8-deposits-tables" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
  <xsd:element abstract="true" id="istr_statement-statement-significant-accounting-policies-policies" name="statement-statement-significant-accounting-policies-policies" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration"/>
</xsd:schema>
